looking at the web stats for march so far I notice this:
That’s insane! This is almost everyone who has bought the game…
Is it possible to make Corporatism policy not avaliable when Keynesianism Economics or Closed Economy policy has already been chosen?
No I don’t think so 
im working on my own mod, would it be okay if i merged my mod with the one you listed. I would give credit to the original author.