My wife is GS and has had some interesting and inconsistent (or what seems to be inconsistent) experiences recently so I am hoping somebody has some information on:

-Booked a CO ticket (or USAIR ticket), codeshare on UA metal, how do you get added to upgrade list? Was told only added to upgrade list on UA upon check-in.

-When you book a CO ticket, when are you added to the Upgrade list? When you check-in? She’s had both experiences where she has been on list prior to checking in and only after checking in.

-Also, what is the upgrade priority for UA GS when flying on CO metal, when you finally do get on the list?