Originally Posted by
Traveloguy
Get your Amadeus booking reference (i.e. Amadeus PNR) and plug it into the MMB microsite on the BA website. If you made your booking on AA, you should be able to call them to get your Amadeus PNR.
I have six itineraries that I have booked on aa.com (either just BA flights or BA plus other OW carriers) and MMB accepted the AA PNR for every one. I then note the Amadeus number that pops up, just in case I need it for something else.
YMMV.