Friend of the Family (1964)

A French farce: Leon "Patsy" Rollo is a toy inventor who goes to his boyhood friend Noël Carradine, now a wealthy industrialist, to convince him to invest in his new invention. The meeting goes badly when old childhood sore spots resurface, but Rollo's wife Dith manages to calm things down. Soon after, she finds some love letters to her teen-age daughter Alexa, and Patsy immediately suspects Noël as the unnamed lover. Seeing an opportunity to get what he wants from Noël by blackmailing him with the letters, Patsy eventually abandons his plan when his daughter finds a new boyfriend. Finally, their differences cleared, the two men go into business together.