The Mistress Is Served (1976)

A bankrupt Italian count has just committed suicide. One of his creditors, Domenico takes over the family villa, but he allows Angela, the widowed mother, Angela's mother-in-law and the three adult sisters to stay on. He is a wealthy businessman, but also basically an uncouth peasant. Still, the dimwitted, sex-crazed sisters try to seduce both him and Daniele, his shy, virginal son. Attracted to the handsome teenager, Sultana and one of the girls allow Daniele to have his first sexual experiences.