This would work to ADD a FFN (if there isn't one at all in the record currently), but definitely for AA.com, once a FFN is in the record, you can't change it yourself online. Don't know if the Finnair avenue still works as there seem to have been mixed reports on that.
Has anyone tried this with an Alaska Airlines award on AA? That, is, not put a FFN in the booking, then add an elite AA number and get MCE on the AA flight?
I used to fly one trip per year on AS when I used to work for a Seattle company, and credited it to AA. Of course you can no longer do that now.
I received 10K AS miles for being a member of the Virgin American FF Program, though I'd only flew them for one flight. However, I do have some more miles due to a cruise from Seattle that ended last week.
I had received a lower DFW-SEA fare on AS than AA, and AS had given me 4 upgrades after matching my AA status which I was able to use as soon as I had booked the tickets. I found I can book the award as someone else (which lets me then enter my name and not my FF number as the passenger), so I want to find out if I can change the FF number on AA or another site, as the AS site will not let me enter it