Original Member and FlyerTalk Evangelist
Join Date: May 1998
Location: Kansas City, MO, USA
Programs: DL PM/MM, AA ExPlat, Hyatt Glob, HH Dia, National ECE, Hertz PC
Posts: 16,579
I would think having someone else's frequent flyer number is very problematic, my understanding is that it links information like birthdate, sex, and Known Traveler information to the passenger.