Not sure if this is the right thread for this, but can you pay with cash or miles to get a confirmed upgrade from economy to business on a BA flight booked through AA? Context is - I have some upcoming work travel but can only book economy through our travel portal. Flying BER to LHR to LAX, and I want to book whichever way will give me the best chance to upgrade the LHR to LAX route. The best itinerary I can see is all on BA, but I can book through either BA or AA. Would be happy to use cash or miles for either, but I'm not sure how likely it is that AA will have an offer to get a confirmed upgrade in advance.