Booking all four tickets through AA is about $1200 more expensive though. Obviously, the kids tickets need to be booked through AA as they are just the SFO-iAd route. But the two adult tickets are cheaper to book through BA since BA allows free stopovers. So, I'm asking if I can book the adult tickets on BA, and then the kid tickets through AA, and still somehow connect the pnrs in case of a flight schedule change.