Originally Posted by kappa

Pedrogoncalves, I'm glad it helped. But, I can assure you that if your bag(s) are checked through to LIS, you will not have any contact, eye or otherwise, with them at LHR. You will arrive on AA at T-3; and if going onward you would transfer by coach to T-5. Your baggage will by transferred on luggage carts via the ramp.

For many reasons (including baggage not making the transfer in the past) I have successfully avoided transfers at LHR at any cost for several years. 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. Either could hold it as 'ransom' unless you paid the fare difference. If it went on to LIS, I assume it could be retrieved, since without PPBM, BA baggage claim might not know you didn't fly.

In the past I have done what you contemplate, but it was always originally planned. It is called a "hidden city" fare, in which a OW (or RT) fare to a point beyond with the connection at my desired destination was cheaper than the OW fare. But I would never do it unless I could short check my baggage. And I have found it best to maximize the connection time between flights (even to overnight) in order to have the best logical reason to short check. Otherwise I go carryon, or ship it via UPS or FedEx.

Which brings up another word of caution: which airline did the ticketing, how you paid for it, and if either FF program number is on the ticket, might affect how they react when you go to retrieve your baggage at LHR or LIS. When I plan to discard a part of any ticket I use, I do not use the airline FF number.