if you credit your flights to a different airline can you still be eligible for compensation?if yes then how do they issue it to you they can't give you that particular airlines currency or travel vouchers? and can you be eligible to receive compensation on American flights flown using ba points if you had a delayed flight etc ?
Yes you should be fine, write to both and that way if one should tell you to go to the other you will be ahead of the game!
Back a few years ago(talking when ba was 4.5k in the US) a flight from Virginia-LGA, whole flight was 1hr or so and was delayed for 6+ hours in the airport, was really mad, my whole reason for the flight was for me to arrive earlier in the day and not kill the day by sitting in a car which I could have done for 7-8 hours.
Booked with BA and flew AA. Contacted ba and then got a response to contact AA, but it was like a game of cat and mouse and I gave up somewhere in between.
But differently send a letter or an email and I'm sure you can get something. Good luck.