Does anyone have advice for securing extra legroom economy seats for alliance airlines that is not the airline in which you earned alliance status? I'm Star Gold by virtue of United but cannot assign extra legroom economy seats on Air Canada, etc. without paying fee.
*A doesn't have an alliance-wide seating benefit for elites. So, you'll have to pay for seat assignments (extra legroom, bulkhead, exit, "preferred," regular, etc.), regardless of status.
There are a few exceptions. UA GS and M&M HON have a few expanded perks on UA/LH Group, including preferred seats. Also, UA *S and AC *S have a few extra perks when traveling on UA/AC, but those are limited to 1 free bag and priority check-in.
There is an actual airline in Australia by the name of Alliance Airlines and they are not aligned with Star, oneworld, or Sky Team. So I am guessing you’re not getting seats assigned there.
It seems you are flying Air Canada and want to use your UAMP/*Gold status to get preferred seats assigned for free. It seems Air Canada is not recognizing your UA Number. Call the airline/agency that you booked the ticket with, and ask them to assign you as seat. If you are prompted for payment, ask the agent to remove and add back your UA number to the booking. That will usually clear the cobwebs.
This is sadly not a Star gold benefit and they are not open to booking for free for non AC elites. The only thing I would recommend is do online checkin when it opens and try your luck.
The alliance benefits are slowly being hollowed out and the focus on own elites and in some cases partners is clearly the focus. This will likely only get worse, as we are seeing with seat assignments but also things like fees for decent seats in business class (hey Lufthansa).
The best way is usually to hope they are not filled initially, and then try your luck at the check in counter politely (if you are ok with not paying and rolling the dice).
For me, in India, it has worked 70-80%, including on domestic LCCs. And the one time I was flying TK while being AI Gold. The agent actually assigned the foremost economy seats (major legroom), to both me and a friend who was on a different PNR and had no status.
I think oneworld is probably the best for this. While they don't have this as a published alliance-wide benefit, I historically managed to select extra legroom seats on other OW carriers for free. For instance, as a CXDM/OWE I managed to get front row or extra legroom seats on JL, BA, AY, QF, and until a couple years ago, MCE on AA. Of the OW carriers I've flown in Y, only MH didn't have any provisions for OW elites.