Hi all. Have a flight in F booked on BA to ORD. For various reasons, we've decided we want to fly on to Detroit the same day. Ideally I'd like to add the Detroit flight on one PNR. I can get a reward flight with AA booked through BA from ORD to Chicago but, if I call BA to book, will they be able to put it on our existing PNR?
No they can't.
It is possible if done at the same time but not later.