Originally Posted by
UKtravelbear
With AA legs you click on the select seat tab in MMB on BA.com and it takes you through to the AA website and you select there. Then it somehow feeds back into the BA booking.
I've found you can't select seats online if you book with BA for an AA-operated flight but with a BA code. BA website sends you to AA, AA website seems to think you can't select seats as BA code. So you have to call.