Originally Posted by
kappa
I think the chances are slim that you will be allowed to short check. If it is not allowed, and you don't fly to LIS, one of two things will happen: PPBM will indicate to BA that you are not on board and off-load your bags; or, there will be no PPBM and your bags will fly without you. In the first instance, I'm not sure how or where you would go to recover them. BA might return them to AA.
I feel as if I am repeating myself, but I'll try again.
There is virtually no prospect (so slight that it can be ruled out) of the bags going on to LIS if the pax is not aboard the plane. If they are checked through to LIS and the pax no-shows, they will be offloaded by BA. Simple as that. The process of offloading will probably cause a delay to the departure and inconvenience to the other pax.
As they would have been originally checked in by AA (and will have an AA tracking reference), were they not immediately reclaimed by the pax in LHR T5 from BA, they probably would stay in T5 until AA told BA what to do with them.