There are some situations where you may find yourself traveling between your origin and destination on separate tickets. Maybe it was cheaper to book an itinerary as two tickets rather than one. Maybe you booked an award ticket for one segment, but had to book a separate positioning flight using cash.
If you’re traveling on an itinerary with checked bags, what are the odds of being able to check your bag at your origin, all the way to your final destination? Let’s discuss that in a bit more detail, as it’s quite nuanced.
In this post:
Airlines have the ability to check bags between tickets
Airlines have different levels of cooperation, ranging from interline agreements, to codeshare agreements, to joint ventures. Technically speaking, airport agents have the ability to check bags through to your final destination, as long your travel is all on airlines that have an interline agreement.
An interline agreement is a very basic level of cooperation between airlines, so airlines even often have this kind of an agreement with competitors. For example, below are the airlines on which American has a baggage interline agreement (per ExpertFlyer).
Now, just because it’s possible to do this, doesn’t necessarily mean an agent will do this. After all, airlines have varying policies when it comes to through checking bags, and that will generally dictate what agents are willing to do.
However, my point is simply to say that there’s not much consistency here, and in some cases, agents have discretion with what they’ll do. For example, I’ve been able to check bags through between airlines that only have the most basic interline agreement, and nothing more (like between Emirates and Lufthansa).
Airline policies on through checked bags vary greatly
What are the policies of the major US airlines when it comes to through checking bags between separate tickets? Airlines really are all over the place. Here are the policies (as I understand them) of American, Delta, and United, ranked from best to worst:
- United has a pretty good policy, and will typically allow you to through check a bag to your final destination, as long as you’re connecting to a Star Alliance partner
- Delta will let you through check a bag to select partners, including Aeromexico, Air France, China Eastern, ITA Airways, KLM, Korean Air, LATAM, Virgin Atlantic, and WestJet
- American basically tells customers to pound sand, and typically won’t even through check bags on two separate tickets both for travel on American
Let me strongly emphasize that there’s still going to be a ton of inconsistency between airline agents when it comes to their willingness to through check bags. You’ll always want to leave extra time for check-in when through checking a bag, and should also bring copies of your separate tickets, to show at check-in.
Also, even on airlines that do allow this, don’t count on this working with 100% certainty. It should work, but it all comes down to the agent you’re dealing with. Of course in some situations, airlines use contract agents, who may not be as familiar with policies.
Lastly, if you are connecting between airlines on separate tickets, at your intermediate point you’ll want to give the check-in agent or gate agent your bag tag, so that they can make sure it’s properly recorded on your reservation.
Why airlines have such varying policies
As you can see, airlines are all over the place when it comes to how customer friendly their policies are for through checking bags.
Some airlines are customer friendly, and realize that through checking bags onto a partner airline is a win-win. It makes the passenger happy, and it minimizes the amount of staffing needed. It can also be an incentive to book a ticket on a partner over a competitor.
For example, I recently connected from American to Iberia in Madrid on two separate tickets, and even though the two airlines are joint venture partners, you can’t check your bag through to your final destination, so we had to reclaim our bags in Madrid. That’s kind of frustrating and customer unfriendly, especially when airlines highlight how seamless joint ventures are.
Why do some airlines have such unfriendly policies? Well, on some level, because they don’t really care about the customer experience. But in all honesty, there are a couple of primary reasons:
- In some situations, airlines may be missing out on checked bag fees if you can through check your bags; of course this wouldn’t be the case if you’re checking bags within your allowance
- Airlines just don’t want to accept the liability of getting your bag to your final destination, in the event that things go wrong
Bottom line
Airlines have varying policies when it comes to through checking bags on separate tickets. While airlines are generally capable of checking bags to the final destination as long as they have an interline agreement, though doesn’t mean they’re willing to.
In the United States, you’ll find that United is generally pretty “friendly” when it comes to through checking bags to partners, while American is the other extreme.
What has your experience been with through checking bags on separate tickets?
I have found that Flying Blue carriers are excellent about this. i usually find a super cheapJ award to CDG or AMS and then book a connecting flight to somewhere else in Europe using VS miles, and the have bags forwarded to the final destination. Virgin however, looked at me like I had three left eyeballs when I asked for the same, BOS - LHR - JNB, all on VS metal using VS miles. BA...
I have found that Flying Blue carriers are excellent about this. i usually find a super cheapJ award to CDG or AMS and then book a connecting flight to somewhere else in Europe using VS miles, and the have bags forwarded to the final destination. Virgin however, looked at me like I had three left eyeballs when I asked for the same, BOS - LHR - JNB, all on VS metal using VS miles. BA was the same as VS, they never heard of such a preposterous idea. Maybe it's a clog in British thinking. Finnair was good about the same thing. Go figure?
Last month I flew IAD-GRU-SCL - (UA: IAD-GRU, LA: GRU-SCL) all on Business, UA agents at Dulles had no problem checking my two bags all the way through no problem. Two separate tickets.
In the recent past Delta at DCA has interlined my bags to Latam in JFK no problem. With the two PNR locators. Sometimes I have been asked if I had my fare basis, but most times they are able to look up.
UA at EWR are categorically denying through checking on separate tickets unless you are Concierge Key or 1K.
Travelling separate tickets UA EWR-BOS and then BOS-MUC on LH F as a UA Premier Plat, we spoke to multiple agents at EWR who all point blank refused and said it was not an option and never has been. I tried to speak to agents at the Concierge Key/1K check in area who also refused to help.
...UA at EWR are categorically denying through checking on separate tickets unless you are Concierge Key or 1K.
Travelling separate tickets UA EWR-BOS and then BOS-MUC on LH F as a UA Premier Plat, we spoke to multiple agents at EWR who all point blank refused and said it was not an option and never has been. I tried to speak to agents at the Concierge Key/1K check in area who also refused to help.
Needless to say, an unpleasant experience. Based on the number of agents we spoke to who denied to assist and check through there, you can expect to be denied at EWR!
In OneWorld, JL & CX will though check with no complaint. I once changed routing AKL-LHR from QF to CX because QF wouldn't through check a piece of luggage. Years ago, CX had stopped through checking, then soon after re-instated it. A CX agent in HKG told me that they got A LOT of flack when they stopped through checking.
So basically, "It depends, maybe, good luck!"
I have realized it depends on how much the check-in agent will help you. Last week I was flying with SQ from DXB-SIN and had a connecting flight with their partner airline Scoot Airlines from SIN-USM but it was a different ticket. The agent was either a dumb one or was not keen to assist as she told me Scoot is not their partner and she was unable to do any through check-in for the...
I have realized it depends on how much the check-in agent will help you. Last week I was flying with SQ from DXB-SIN and had a connecting flight with their partner airline Scoot Airlines from SIN-USM but it was a different ticket. The agent was either a dumb one or was not keen to assist as she told me Scoot is not their partner and she was unable to do any through check-in for the bag. A friend who works for Emirates even spoke to her to guide her on how to do it manually but she totally refused. The opposite was Emirates on the way back who had no issues tagging the bag onwards with SQ even though they were 2 separate tickets and SQ is their competetitor.
As others have pointed out, SQ is one of the few airlines who publicise on their website that they do through check on separate tickets as long as it’s a partner and Scoot is at the top of the partner list (I think Qatar do too, following the change in OneWorld policy where they all had to do it).
That website content is misleading. In my experience SQ will not accept baggage on separate ticket to Scoot flights (TR code) as they're a low cost airline. I suspect because of the paid baggage issue that Ben mentions. What you can do is book (most?) Scoot flights in one ticket with SQ flights on an SQ codeshare and in this case they'll accept the bags through. Which is what they mean by the content on that partner page I believe
This is true but not practical if you are using miles to redeem for SQ and paying for Scoot because it isn't easy to get both flights on one itinerary due to their technical glitches. The information on their website is absolutely misleading and the agents do not care much either to help.
BA won't through check even when travel is entirely on BA if the segments are on separate reservation locators. This is a real pain when using traveling on awards where flights are available on the segments individually, say SFO-LHR and LHR to CDG but not as a single award.
Even though BA has the ability to combine tickets on separate reservations into one reservation, which would allow through checking a bag, they generally refuse to...
BA won't through check even when travel is entirely on BA if the segments are on separate reservation locators. This is a real pain when using traveling on awards where flights are available on the segments individually, say SFO-LHR and LHR to CDG but not as a single award.
Even though BA has the ability to combine tickets on separate reservations into one reservation, which would allow through checking a bag, they generally refuse to do so. As a result on our last family trip via BA I was forced to check our bags to LHR, clear immigration, pick up our bags, clear customs then rush to the counter to recheck them for absolutely no good reason given the tickets included checked bags so BA wasn't entitled to any additional fees.
Never had a problem with BA through checking in Europe. I wonder if they take a different stance out of the USA to “support” AA’s poor attitude on the matter.
@Steve They can it’s just laziness as they have to edit other parts of the system, it really depends who you deal with on the day.
They absolutely can. You just had a lazy and/or ignorant agent at check in. If that happens again, ask to speak to a supervisor. SFO shouldn’t be any different than LAX in this regard.
Is there a limit to how many sectors you can through check for?
AA flights LGA-DFW-LAX on separate tickets. AA agency at LGA refuse to through check even though both are AA flights. Said that their policy.
YMMV depending on the check-in agent at the co6nter. NH agent was able to check bags on a separate onward AS ticket, despite not being in the same alliance. On the flip side, UA agent wasn't able to check bags thru on TK flight. AC agent couldn't check thru on Aer Lingus. You win some, you lose some.
AC is the worst for this. Had two separate tickets - both issued by AC FLL-YUL-BRU and conex with SN BRU-MAD . The SN ticket was an Aeroplan award issued by AC. Absolutely refused. Even Supervisor would not do it.
Amazingly spoke with an SN agent in BRU and they managed to retrieve the bags and complete the transfer. They even came on board the BRU-MAD flight to tell me the bags had been loaded. I was shocked. Incomparable ground service by SN in BRU.
Last time I flew Finnair business on an award ticket, with a revenue connection in Helsinki to my final destination, the gate agents had no trouble booking my luggage through to the destination. Doing it again in October, hopefully the same will happen.
Thanks Ben, this is a great subject. However, you might be underestimating the negative impact of AA's total refusal to through-check bags when you say 'kind of frustrating'. I travel very often to the US on British Airways, but because of frequently changing work plans I often have to shift my domestic US travel, and re-book tickets. The total refusal of American Airlines to through-check bags means there is literally no point whatsoever in choosing...
Thanks Ben, this is a great subject. However, you might be underestimating the negative impact of AA's total refusal to through-check bags when you say 'kind of frustrating'. I travel very often to the US on British Airways, but because of frequently changing work plans I often have to shift my domestic US travel, and re-book tickets. The total refusal of American Airlines to through-check bags means there is literally no point whatsoever in choosing AA for domestic legs against any other airline (unless perhaps changing at JFK).
I've repeatedly been refused through checked bags even on two legs operated by AA, both in business. Refusing to through check a bag for a premium passenger on flights entirely operated by your own airline is not about taking any risk - it's about incompetence and aggressively terrible premium service. They are working remarkably hard to remove any incentive to travel with them on business.
Also worth noting, I've been told by multiple check in agents the AA computer system no longer accepts through-checked bags on separate tickets, so they have zero discretion.
I have to say, my experience with through checking from BA to another airline, is that the agent will usually say “I will try and see if the system let’s me”, and in most cases the system does not, apparently. Although shockingly, I did have a one off experience connecting from a BA shorthaul to a QR longhaul flight where the agent just said all flights showed up on the system automatically and they could...
I have to say, my experience with through checking from BA to another airline, is that the agent will usually say “I will try and see if the system let’s me”, and in most cases the system does not, apparently. Although shockingly, I did have a one off experience connecting from a BA shorthaul to a QR longhaul flight where the agent just said all flights showed up on the system automatically and they could therefore through check. The only thing in common (other than name, DOB etc was my FFP). No idea what happened there!
"American basically tells customers to pound sand, and typically won’t even through check bags on two separate tickets both for travel on American"
That made me laugh!
Thanks!
Traveled recently KIX-TPE-SFO-CLT-DCA on two separate tickets: BR award ticket KIX-TPE-SFO and paid SFO-CLT-DCA on AA. It took a BR agent at KIX some time but she did check in my luggage all the way through DCA. At SFO, I just dropped it off after going through customs.
I recently did this on Lufthansa (J) connecting to a US domestic United (Y) flight. The check-in agent (in BKK) asked if I had status, credit card, etc. to get free baggage - I just told her I'll pay when I get to the US port of entry. Of course, you're never charged for this since the bag is already tagged to your final destination.
British Airways has categorically denied me this option for travel in Nov. We are flying overnight from JFK to LHR on a revenue ticket. And connection LHR to VIE on an award ticket. And in spite of being a BA Executive Gold and checking with the agents (a) on the phone (Gold line) (b) at the Concorde lounge at LHR and (c) making another last attempt on the phone - it was DENY, DENY, DENY.
Simply outrageous when it is the same airline, same day, 3+ hrs apart!
You should be able to sort it on the day at the airport, I do GIB-LHR (avios) LHR-IAD (revenue) on a regular basis and never had a problem. The only no is if the connection is over 12 hours as they can’t store your bags overnight at LHR.
In all honesty, I don't think this is BA policy. I have never had a problem through-checking bags with BA, although I have not tried connecting a revenue and award ticket before. Idiotic reason to deny if they did that...
If it’s BA then BA you’ll be fine. Just present both confirmation numbers at check in to the agent. They might not be thrilled about it, but they’ll do it.
I do this when checking in at LAX, connecting via Heathrow.
I'm flying Iberia LAX-MAD-BCN but on separate tickets. I was told to expect to grab bags in MAD even though it's all Iberia.
Wasn't aware about the Alaska policy change, so thanks to those who pointed that out. I'm updating the post to reflect that.
While Alaska refuses to through check a bag to another carrier if travel is on a separate ticket other carriers are willing to check to Alaska.
We had no trouble checking our bags on an award ticket Seoul to SF through to Portland where the SFO to PDX leg was on a paid ticket. In fact the agent at the airport counter proactively asked if SFO was our final destination and when we said it...
While Alaska refuses to through check a bag to another carrier if travel is on a separate ticket other carriers are willing to check to Alaska.
We had no trouble checking our bags on an award ticket Seoul to SF through to Portland where the SFO to PDX leg was on a paid ticket. In fact the agent at the airport counter proactively asked if SFO was our final destination and when we said it was not, offered to check our bags all the way to our final destination. So this is simply a matter of airlines, primarily US airlines, being user hostile even when it doesn't earn them any additional revenue.
First of all, Ben, thank you for making this post. This is a very important topic and one that contributes to a great degree of stress. It's also a topic that is shockingly poorly represented on the internet, even on FlyerTalk and Reddit) so it needs some clarification.
Although I'm just a single data point, I will say that Delta does a great job with Virgin connections, but my understanding of Alaska's policies is that...
First of all, Ben, thank you for making this post. This is a very important topic and one that contributes to a great degree of stress. It's also a topic that is shockingly poorly represented on the internet, even on FlyerTalk and Reddit) so it needs some clarification.
Although I'm just a single data point, I will say that Delta does a great job with Virgin connections, but my understanding of Alaska's policies is that they will *not* through check a bag to British Airways. In fact I'm pretty sure on their website it clearly states this. If anyone has had a different experience I would like to hear it.
Also "Lastly, if you are connecting between airlines on separate tickets, at your intermediate point you’ll want to give the check-in agent or gate agent your bag tag, so that they can make sure it’s properly recorded on your reservation."
Really? I have never once done this. Surely it's automated and it either works or it doesn't. Plus by definition you will not encounter a check-in agent since you're presumably through checking bags to avoid...
Also "Lastly, if you are connecting between airlines on separate tickets, at your intermediate point you’ll want to give the check-in agent or gate agent your bag tag, so that they can make sure it’s properly recorded on your reservation."
Really? I have never once done this. Surely it's automated and it either works or it doesn't. Plus by definition you will not encounter a check-in agent since you're presumably through checking bags to avoid dealing with security/check-in again... and I highly doubt the gate agent has any control over this.
I always check because I did have a situation where connecting from CX to BA, on the same ticket, I was told at the origin to make sure I check with the gate agent. At the gate I was told that had I not checked my bag would not have been loaded. 95% of the time I get blank stares and responses along the lines of “if your destination is on your luggage tag then it will get there” but every now and then they seem to need to input something in the system.
Alaska no longer allows you to through check a bag on a separate ticket.
Travel that includes multiple airlines or tickets
If you're traveling on more than one airline, your baggage fees and rules may be determined by the other airline. Please check your ticket, or call Alaska Airlines Reservations at 1-800-252-7522 to help determine which airline rules and fees apply to your journey.
If your travel includes more than one ticket, each...
Alaska no longer allows you to through check a bag on a separate ticket.
Travel that includes multiple airlines or tickets
If you're traveling on more than one airline, your baggage fees and rules may be determined by the other airline. Please check your ticket, or call Alaska Airlines Reservations at 1-800-252-7522 to help determine which airline rules and fees apply to your journey.
If your travel includes more than one ticket, each ticket is considered a separate journey. Baggage will only be checked to the final destination on the first ticket. Please allow enough time to collect your baggage and re-check in with the next airline. Checked baggage will not be transferred on to your next flight that's on a separate ticket. Baggage fees for each carrier may apply.
In March of this year, an agent for AS let me check a bag all the way to my destination, when I had an AS ticket for leg 1, and a separate AA ticket for leg 2.
You were lucky.
I do this about once a year starting on UA, connecting to another Star Alliance carrier on a different ticket. UA has always done it, but it takes on average 20 - 30 minutes for them to figure out how to do it. It's a bit painful but I'm thankful. I thought about asking an agent to write down the steps so I could show them next time.
I have a trip coming up on Tap Air Portugal where I have purchased two separate tickets both flying on Tap AirPortugal. Since I only have less than 2 hrs layover at Lisbon, can the agent check the bag to my final destination if I show both the tickets at the airport?
They should be able to do it, although I would prepare for the worst as they certainly weren't willing to tag something through for me when I flew them to MXP for a same-day connection on ET.
english? confused?
I once tried to check in, Air France (2 legs) followed by ITA (2 legs). The Air France was on a different booking than ITA. Air France agent said only 3 connections can be put on the same bag tag and since mine involved 4, they won’t be able to…
They printed two bag tags for me and did it with 4 segments
On a trip last December with AC the outstation agents were unable to check my bags all the way through IAH-YUL-GRU-EZE (all AC metal). Mind you I had booked a separate mileage award ticket with for the GRU-EZE segment, but they told me to my face that AC does not fly to EZE from GRU (:-|); even after pulling up their own route map. The 2 hour layover at GRU was just enough time to clear immigration and re-check my baggage onto EZE.
AC agents are on average very nice. However some of the least helpful and most entitled and ignorant airport agents I have ever had the displeasure of dealing with were AC agents.
I second that!
I wonder if international connections make a difference. I have a trip coming up where the first leg is domestic Japan flight ITM-HND on NH connecting to an AAward flight HND-JFK-DCA. I have 4 or 5 hours between flights at HND. It's nice to know they have an interline agreement. I guess I will find out at checkin
See my comment above about AS and check Flyertalk. Assuming NH has an agreement and no posted policy forbidding through checking you'll likely find they'll either know how to do it or be willing to try. But check FT to see what people's experiences have been.
OK the bag goes missing? Who’s liable? You have two contracts with two different airlines. You will be screwed.
You will be screwed because you don't know what interline means.
Final carrier takes the claim. They won’t deny responsibility tied to the 2 tickets once it is accepted by the carrier.
Just flat out wrong
Claim is always per IATA rules filed with last carrier flown after last flight. All liability rests with that carrier
The MITA is dead. No longer any IATA rules for interline, just bilateral or alliance agreements loosely based on MITA. If I was the last carrier I’d point my finger at the first, and they would point their finger at me.
That’s also wrong. A bag claim can be handled by the first or final operating carrier. The last carrier will open the irregularity report but it doesn’t stop you claiming from the one who checked you in. The one who opened the claim may not be responsible for the delay and will bill the first carrier for costs.
Art 36 of the Montreal Convention:
“1. In the case of carriage to be performed by various successive carriers and falling within the definition set out in paragraph 3 of Article 1, each carrier which accepts passengers, baggage or cargo is subject to the rules set out in this Convention and is deemed to be one of the parties to the contract of carriage in so far as the contract deals with that part of...
Art 36 of the Montreal Convention:
“1. In the case of carriage to be performed by various successive carriers and falling within the definition set out in paragraph 3 of Article 1, each carrier which accepts passengers, baggage or cargo is subject to the rules set out in this Convention and is deemed to be one of the parties to the contract of carriage in so far as the contract deals with that part of the carriage which is performed under its
supervision.
2. In the case of carriage of this nature, the passenger or any person entitled to compensation in respect of him or her can take action only against the carrier which performed the carriage during which the accident or the delay occurred, save in the case where, by express agreement, the first
carrier has assumed liability for the whole journey.
3. As regards baggage or cargo, the passenger or consignor will have a right of action against the first carrier, and the passenger or consignee who is entitled to delivery will have a right of action against the last carrier, and further, each may take action against the carrier which performed the
carriage during which the destruction, loss, damage or delay took place. These carriers will be jointly and severally liable to the passenger or to the consignor or consignee.”
I believe Alaska recently changed their policy and now is similar to American in telling people to pound sand:
"If your travel includes more than one ticket, each ticket is considered a separate journey. Baggage will only be checked to the final destination on the first ticket. Please allow enough time to collect your baggage and re-check in with the next airline. Checked baggage will not be transferred on to your next flight that's on...
I believe Alaska recently changed their policy and now is similar to American in telling people to pound sand:
"If your travel includes more than one ticket, each ticket is considered a separate journey. Baggage will only be checked to the final destination on the first ticket. Please allow enough time to collect your baggage and re-check in with the next airline. Checked baggage will not be transferred on to your next flight that's on a separate ticket. Baggage fees for each carrier may apply."
https://www.alaskaair.com/content/travel-info/baggage/checked-bags
I *hope* this is a case where the published policy is significantly more stringent than the de facto policy.
I've asked AS to through-check bags numerous times and they've consistently done it (but the last time was in 2023, so if there has been a recent change as you suspect, I would not have encountered it yet).
Alaska used to willing to check bags through but last time I tried, in July, they wouldn't do it. Agent said the policy had changed as of the first of the year. This was on Alaska to LAX and American to SYD.
Thanks Jim. I would like Ben to further investigate this as I was certainly under the impression that Alaska no longer through check bags to connecting airlines. Certainly AS-BA is a no-go... maybe AS and AA still works?
In March of this year, an agent for AS let me check a bag all the way to my destination, when I had an AS ticket for leg 1, and a separate AA ticket for leg 2.
Air Canada lately doesn't allow to check the bags trough on a separate tickets with the other Star Alliance airlines. I'm a AC Super Elite and was flying recently to a different destination in Europe on 2 different tickets. When aske during a check in it Toronto to check my bag through I was told on a numerous occasions, that AC is not doing it because of the liability issues. Not exactly sure if it does make sense but it is what it is.
Yes, I had the same experience on a flight from Vancouver (YVR) to Toronto (YYZ) on Air Canada and then. connecting with a different booking locator onto TAP from YYZ to Lisbon (LIS).
Interlining baggage only seems to work when all flight sectors are on the same booking locator (ticket).
Alaska has been brilliant in this respect so far, and I never had issues interlining my bags from YVR to Seattle on Alaska/Horizon and the...
Yes, I had the same experience on a flight from Vancouver (YVR) to Toronto (YYZ) on Air Canada and then. connecting with a different booking locator onto TAP from YYZ to Lisbon (LIS).
Interlining baggage only seems to work when all flight sectors are on the same booking locator (ticket).
Alaska has been brilliant in this respect so far, and I never had issues interlining my bags from YVR to Seattle on Alaska/Horizon and the onto Emirates (EK) to Dubai (DXB) and beyond, even if there were two different booking locators.
It would be a pity if that policy had changed.
B.
Brutus, have you had good experiences with AS Horizon within the past 18 months or so doing this, or just a few years ago? If recent that's a big deal.
Ive had terrible luck with Delta. I frequently will book DL MSP-ORD and AF/KL ORD-Europe. I do so on separate itineraries (you all should know why)....but i still have to exit security at T5 in ORD and recheck...
Had a BOS-ORD-TPE award ticket on UA and BR. The first flight was cancelled, and UA rebooked me to AA, and to my surprise, AA checked my bag all the way to TPE with no problem.
That was still all on one ticket, so there should be no ambiguity here.
Had some great agents in SAT who would through check in bags when I used to fly AA/EY/GF etc on complex itineraries. They even did for some time when the policy changed. All that stopped when USless airways took over :( avoided US airways at PHL at all costs but now stuck with them.
Ben - what about Singapore Airlines?
Yes. Does Singapore through check on Lufthansa, both Star Alliance?
I've done check-through SQ-LH on same reservation numerous times with no issue, but am curious if anyone has done it with separate tickets (sometimes SQ/LH award availability is tough to find concurrently)
Yes, SQ will through-check in most situations on Star Alliance and their other partners. There's a FAQ on their website on this topic.
I find SQ to be very helpful on this - they will through check in to any listed partner.
I was also shocked when Swiss through checked me on a separate CX ticket! Definitely one of those, if you don’t ask you don’t get moments!