Originally Posted by
guv1976
Have you tried rebooking the reservation at avis.com, using the Costco AWD? Or calling Avis Customer Service and asking whether they can add your FFN to your existing reservation?
Was able to make this reservation directly with the Avis website using the Costco discount codes. Doing it two days later, I noticed the price went down $2. I'll take it!
But I still couldn't find any input field for airline frequent flyer numbers. There was a flight arrive section, but not a FF one.