I have one of these flights coming up. I have minimal status on both but here's what I did. I booked on AS thru their web site (1k bonus) I did my seat choices for the AS flights as the AA part was blocked out. I then signed on to AA web site and looked at what was AAvailable. I also wanted to know if it would let me do anything with the AA portion. Sure enough, AA let me choose my seating for that portion and it also showed the AS flight but it was blocked out. It did show the fare codes for both flights, which I thought was interesting. I also noticed down at the bottom of the screen, there was the area about Upgrades. Only the AA segment was eligible. For the AS portion to upgrade, you have to call them if you're using Flight Plan miles. Not sure about Elite.