I think it's pretty clear that we're all somewhat knowledgeable of the FFP program jazz. How do the actual business matters of this part of the industry work though? Something came to my mind when I was in the shower-

Scenario:
I book a ORD-PVG flight on AA using BA miles. In PVG, I use a JAL lounge. Which airline would pay which airline for the redemption part of the flight and the lounge?

Sorry if I sound confusing.