Not sure the question has been asked, but couldn't find it with a quick search.
My return flight arrives HKG at 6am, and connect to HAN at 6pm (using my AA FF). If I use avios to booking a KA flight to somewhere else at 12 (stick with BA FF), will that be a problem, say, at check in or boarding with the KA flight? And also, I assume I can just show them my AA EXP card on the phone to access the lounge while no switching my booking to AA, right?