After learning that CCS-LHR 767 has cradle seats in CW, I tried to upgrade to F but was told that I fares could not be upgraded. So, I booked a CCS-MIA-LHR-TXL return in CW (D fare) directly from BA. When I asked to upgrade that to F, the Gold desk agent told me that the BA reservation system does not physically permit them to upgrade my MIA-LHR and LHR-MIA segments to F because the ticket contains AA segments. I would need to have separate tickets issued (which would cost several hundred dollars more). That sounds so lame--is it really true?