Mistress (1992)

A comedy about a screenwriter (Robert Wuhl), whose old movie script is read by a producer (Martin Landau) and the search for financial backers begins. But it seems that each money source (Danny Aiello, Robert De Niro, and Eli Wallach) has his own mistress that he wants put into the film. Gradually, the screenwriter is forced to make changes to his script to accommodate these backers, until he finally sees no semblance of his original ideas in the writing.