I’ve been flying TUP-BNA-ORD lately. Since the first leg is on Contour Air, I have to check in at the airport. Even though I get my AA boarding pass for the second leg, I have to “re-check in” at BNA to get my name added to the waitlist. It’s a pain, and when delayed at TUP, other upgrades clear before I can get added to the list. I don’t know of a work around. I tried using the app chat, and they were not able to help me. Agent at BNA wasn’t able to offer a suggestion for the future, either.