Maid for Murder (1962)

Brothers Francis and Douglas Oberon find themselves cut off from the family fortune by their late grandmother's will. Their distant cousin (once removed), maidservant Antoinette "Toni" Oberon, is the benefactor of the entire estate and is arriving to view her new property. Facing being homeless, broke, and actually working for a living, the boys devise a plot to either marry Toni (and share the fortune), or kill her off and claim the estate for themselves.