Let's say Airline A placed an order for an aircraft a while back. After a bit of time, Airline A decides it no longer has a need for the aircraft and decides to cancel the order. Meanwhile, Airline B decides it wants to buy said aircraft but doesn't want to go to the back of the delivery line. Is there a process where Airline B can take Airline A's spot in the delivery queue? I vaguely remember seeing something like this happen before, but cannot find any sources.