Originally Posted by
kaztm
They do ask for your boarding pass, but in my experience, they also accept itinerary (that you can print out at home or hotel) showing connection to AS/AA. I have not tried separate PNR, but I think it should work.
A printed itinerary (instead of a boarding pass) should work. It has for me numerous times. Since the start of the year I've been doing that roundtrip about twice a month.