Forgot to point out my thread about trying to get my UA # into a mixed US Metal with US/UA codeshare purchased on americanexpress.com. CSR's with Online travel agents who should know better don't even know what to do.

I did just purchase a flight on united.com that was the other way around: all UA flight#s but some are UA codeshares on US metal. When I called US, they already had my UA# in the reservation.

So some of the airlines' interconnections actually work.

The advice from both clacko and Counsellor to save your original boarding passes is critical, however "good" certain sites may be. Sooner or later, probably sooner, somebody is going to drop your desired FF# and you're going to have to mail things in.