Well, if you want to recycle captured material without taking up a turn to do that, you could do it similar to Musketeer Chess. A Captured piece would reappear on its starting square when it is empty, or as a side effect of the first move that evacuates the square after it was captured. That would still pose the problem that you must remember on which square a piece of a given type started, as for R, N and B there would be two possibilities. Of course you can also stipulate that the user can choose which empty square it goes to, while it would go at the first of teh two that gets evacuated when both are occupied at the moment of capture.
Well, if you want to recycle captured material without taking up a turn to do that, you could do it similar to Musketeer Chess. A Captured piece would reappear on its starting square when it is empty, or as a side effect of the first move that evacuates the square after it was captured. That would still pose the problem that you must remember on which square a piece of a given type started, as for R, N and B there would be two possibilities. Of course you can also stipulate that the user can choose which empty square it goes to, while it would go at the first of teh two that gets evacuated when both are occupied at the moment of capture.