Originally Posted by
Tafflyer
If I call then I‘m sure the number I give them will be sticky. I want to have control over this myself so that I can use A3*G to get fast track and lounge and then switch to UA for mileage credit (P fare earning nothing on A3). I can ask for it to be done at the gate but why the heck should an airline actively prevent passengers from changing the FFP in their own bookings.
Just put your A3 number into the booking, and retroclaim via UA. Retroclaim works fine on any flight which hasn't credited to another program.