Originally Posted by
alexwuk
Yes, exactly. If you book with BA, you can mix airlines. Book with a Travel Agent (to book the upgrade into revenue inventory T/D/A), you can't mix airlines (ie BA metal only bookings)
I've done it with AMEX in the last few months. Perhaps I was just lucky. GUF2 applied to an itinerary including BA and AA. GUF2 only on the BA legs of course.