Originally Posted by
jackal
Hmm...I've been told that mileage is ALWAYS based on the metal flown, not the ticketing carrier.
FWIW, a few years ago (before the BA mileage credit drop for economy tickets) I booked BA to Madrid, with one LHR-MAD leg on Iberia metal, and the return on BA metal.
The Iberia boarding pass had a BA flight number. None of the flights posted automatically (my fault), and I wrote in to have it posted to my account. All segments, including the Iberia metal segment, were posted manually. (I don't think Iberia was/is a partner.)
I certainly wasn't trying to cheat, so maybe I just got lucky.