Being really clear on that: It's perfectly possible and a great idea that has been done before with another game, Urban Demons.
here is a Urban Demons mod done by F95 Community which adds a lot to the original game and was being developed before the original game was even completed (like The Manor, currently). the community could do the same thing with The Manor with no real problem at all
i say no "real" problem because we all know Bones's toxic personality and how he probably would threat sueing someone here(which could never happen because we have enough anonymousity in F95)