The Fortune (1975)

The early 1900s with its Mann Act (disallowing women to be transported across state lines for immoral reasons) brings a married man to devise a scheme for taking his upper-class girlfriend away with him. He simply has her marry his unmarried buddy. However, it doesn't take very long before both men start laying claim to her affection. Until, that is, she's about to be cut out of her parents' fortune. So, a new scheme is devised, which only adds to their problems, as well as to the sly whimsy of this movie.