Received an email form BA this morning telling my a BA code share with AA had been cancelled. Whilst the AA flight did change it's flight number it's essentially the same flight 20 minutes earlier, this is early November. I'd known about this from AA for several days, but have read here much of the code share information is handled manually. Had preferred the BA flight number as it's a DTP holiday, although BA always want to use their numbers anyway. This made me think why with the JBV with AA wouldn't BA just use AA prime flight numbers and remove what seems a superfluous layer of admin, around creating their own flight numbers. It'd be a 125 ticket so clear who sold the flight, in regard any revenue split. I know BA wouldn't for example sell an AA flight domestic flight that was connecting to a transatlantic, but surely that could be better managed than by the creation of code share flight numbers?

It seems more so with the JBV, but in regard any flight what purpose does the code share serve for the selling airline?