Originally Posted by
econ
Last time I booked an AS mileage ticket, it would not allow one to enter a non-AS FFN. So one would have to contact AS after booking anyways.
If I want to use another FFP, I do book as a new traveller and leave the FFN field blank, since I figure that it’s always more straightforward to add a FFN later than to replace one.
I've talked to several people who have created a new traveler profile for themselves with their AA frequent flyer number so it apparently works for some folks without calling.