To clarify, can you change FFN multiple times within the same itinerary? For example:
I have TK *G status that I wish to use for free baggage, lounge access, and possibly free online SDC privileges on United flights. On the other hand, I want to earn the MP miles. Here's the round-trip itinerary operated entirely by UA:
EWR-ORD-MCI//
MCI-EWR
I plan to put my TK# on the res. and switch it to UA online after check in for the first flight. For the return portion, will I be able to switch the FFN to TK for check-in and then back to UA before take-off?