Originally Posted by
Dave Noble
BA would not be the one to cancel the itinerary, but would not expect to be allowed to board the aeroplane with the BA coupon still in an open state rather than a flown state and that AA would require handling as per a no show
Even if the OP had already checked in on American before he no-shows on the BA flight? I think you are overoptimistic regarding airline IT that the BP scanner for boarding will go back and check to see if the OP has any open coupons before deciding whether to allow him/her to board.
For the OP to not be allowed to fly on his/her American flight, AA would have to have a system in place that would notice the open coupon on BA despite the flight time passing and proactively void out the rest of his coupons. I don't believe such a system exists (as it would very likely cause more problems than it would solve esp wrt irrops and improper coupon collection) but anything is possible.