Originally Posted by
18wheeler_vanrekt
If I get the upgrade confirmed ~12 hours out, can I then change the earning frequent flyer number to say, Skymiles without losing my upgrade?
On paper you would lose the upgrade, but since you only can change your FFP number at the check-in desk, I believe YMMV
Originally Posted by
18wheeler_vanrekt
If I haven't gotten the upgrade by 12 hours before the flight, it's guaranteed I will not get it therefore I could change the frequent flyer number worry-free?
You may still get the upgrade at boarding time