If you aren't using Character's names, or the title or the central idea of the story word for word, then why bother contacting someone to give money away to? If a publisher or controling entity wants to TRY to sue you over a similar IDEA in a short film, tell'em bring it on, because no one owns ideas, they can only own their exact interpretation of the idea.
Obviously don't say "Based on the works of..." "Or adpated from a book by..."
I once wrote a feature using a celebrity's name as the name of my antagonist, the story was the simple, immature overused device by which the protagonist is fighting himself (His unresolved issues manifest in the form of a hallucination of someone with the same name as the celebrity, and taunt him as such.) So after a month or two of kicking this script around to try to get it made, I was shockingly contacted by that celebrity's management with a very stern (Swearing and all) warning to cease and desist.
I wrote them back and said I had registered and was shopping the script around as an autobiographical piece, so if their beloved client (Who I only used the name of) wished to drag a nobody into court to try to prove what might or might not have actually been hallucinated, then they better pack a lunch, because it would be an all day losing battle that would not only get my script attention, but would make them look foolish, AND I would then happily counter sue the F out of them just for something to do, but also would go on to write a script based on my personal accounts of being sued by them, not just a character with the same name.
I never heard another word about it. lol
