I mentioned on Hal’s thread at one point that this is absolutely what would have made Palpatine’s plan 100 percent better imo. Funnily enough, early in the film’s production it actually was I’m pretty sure. The reason they got rid of it I think is because otherwise it makes the character’s heroic actions all for nothing in the end. Personally, I’m fine with that. Sometimes, even though we give things our best, they don’t work out.
As for Rey not being a Palpatine, it also removes some of the complicatedness of her backstory. I’ll always prefer to adhere to canon in this regard, but I’m interested to see what you will cook up.
I think if I was editing the novel I would make all references to her as his granddaughter changed to just “daughter”. This would force the reader to understand that Rey’s father was a clone, so biologically she is just his daughter. It might muck up some of the mirroring in their dyad, but oh well.
If I was going to go with Rey Palpatine then I agree; just referring to her as his daughter would actually be a lot better. I’m surprised I haven’t seen this in any fanedits of the movie, actually. I guess it would be potentially confusing without further clarification.
I also think something along these lines was probably the original idea for Palpatine’s plan; Rey Palpatine apparently wasn’t written in until after shooting had begun, and we know from behind-the-scenes stuff that a lot of the film was still being rewritten wholesale as it was being shot (and simultaneously edited; what a pressure cooker of an environment to be trying to direct a movie in).