La padrona è servita (1976)

As the movie begins, a bankrupt Italian count has just committed suicide. One of his creditors has taken over the household property, but he enables the widow, the mother, and the three adult sisters to stay on. The creditor is a rich businessman, but also basically an uncouth peasant (who fancies himself an opera singer). Nonetheless, the dimwitted, sex-crazed sisters try to seduce both him and his virginal, shy son whom accompanies him. But both guys end up falling in love with the voluptuous widow (Senta Berger) creating a kind of incestuous love triangle.