Does this mean in future when I book (let us say LHR MIA return) one return ticket I will be booked on to BA one way and AA return? or may be offered MIA-MAD-LHR with combination of AA/IB or IB/BA based on the same price? That is what happened to Star and Sky on some routes (including TATL and Asia). That the booking engine try to book you into different carriers on the return trip. The only problem is the high fuel surcharge BA/IB imposed to customer. I will not be happy if I fly with AA a lot.