Originally Posted by
tommyleo
Good point about losing the upgrade, but the OP seems to be referring only to preferred coach seating.
As for the comuter sweep, what if, upon landing after the outbound flight, the OP called the DM number and told them to apply his DM number to the return flight? That should hold his preferred seating assignment. Then the OP would have the option on the day of his return flight to change the FF number to UA's if he so desires.
I'd be curious if anyone knows the answer to this.
I'm thinking it won't because the few times I've switched my FF numbers, I was asked if the flight in question was my outbound. It's led me to believe that once the trip has begun that such a change can no longer be made.
But I could be wrong.