Originally Posted by
SwissexLUG
In this case I'd start with ARN BA LHR BA MCT AA LHR AA LAX to have the AA code, and the bonus miles, on the longer MCT-LHR leg instead of the shorter ARN-LHR one.
I wish you a great journey!
Take care
Of course ticketing it this way will mean higher fuel fines as BA will be issuing the ticket and the reason why Gardyloo recommended ticketing the ARN-LHR-LAX using the AA codeshare from ARN connecting to the AA transatlantic flight.