Originally Posted by ashill

My recollection from the AA/US merger (the only one of the big three which was a merger of non-partners), they had reciprocal FF earning (and burning, I think) in place almost immediately after the corporate merger closed. It was one of the first things to happen, presumably because it's relatively easy to add a new FF partner. Upgrades took a bit longer and had various stages of ugly kludges, but as noted, with VX's very different view of F, upgrades are less clear at best.