Sarah Silverman has joined the cast of the Leonard Bernstein biopic “Maestro,” which will star and be directed by Bradley Cooper, an individual with knowledge of the project told TheWrap.According to Deadline, which first reported the news, Silverman is playing Bernstein’s sister.“Maestro” was originally set at Paramount, but Netflix took over with Martin Scorsese producing along with Steven Spielberg, who is producing via his Amblin Entertainment banner.