Yeah, I read the readme .pdf and saw the aaa mod.
I did manage to get the "shared pc" box in Reborn but not in Rejuvenation, and the error message was popping up when launching Rejuvenation.
I'm currently trying out the Randomizer Mod for Reborn so I have no need for this mod at the moment, I was just finding it difficult to get working, as in my mind the idea of the mod was "transference of pokemon between Reborn and Rejuvenation" but I may have misinterpreted what the SharedPC mod was.