Originally Posted by
JAXBA
True, BA will also only book you on the BA code on its own flights, and prefers to use the BA code where it exists on other airline operated flights. Book a flight where there's no BA code though and BA won't mind which code is used.
AA booking a QR flight shouldn't mind booking the BA code if that's your preference. I'm not seeing AA codes on the QR operated flights LHR-DOH, only on the BA operated.
There used to be. I assume those were casualities to the ME3 dispute in which AA dropped some codes from QR and EY flights.