The Maysles Brothers' 1975 documentary, about two nutty relatives of Jacqueline Kennedy Onassis living in East Hampton squalor, wouldn't seem like much to build a musical out of. But writer Doug Wright has done a shrewd expansion job. The first act, full of bright colors and bouncy 1930s-style tunes, imagines the mother and daughter in their earlier salad days. The second act condenses the cinema-vérité longueurs of the film into a dark, funny and frightening portrait of two recluses who can't live with — or without — each other. All of which provides the role of a lifetime — two of them, actually — for its wondrous star Christine Ebersole.