Family Affair (1966)

Bill Davis is a highly-paid and successful engineer living in a large apartment in New York with his valet, Mr. Giles French. His life is suddenly changed when his niece Buffy shows up. In the midst of deciding what to do, Buffy's twin brother Jody shows up, and Bill must leave for Peru. Once he leaves, Buffy and Jody's older sister Cissy shows up. Bill and French's life is suddenly changed as they become surrogate parents for the three children.