Wait, how can they claim copyright on materials that are derivative works of copyrighted works they don't have a license to? And why would anyone running a fan film project give him and his company the copyright to the film they're producing in the first place? My understanding is that, typically, when you're working under contract, the copyright belongs to the company for whom the work it done. If I had someone rewriting a script, be first thing I'd do is make him sign a document saying that I had either the copyright or a license to it that permitted derivative works.