French Infernal(1983)

Bon chic, bon genre, mais... salopes!!

Ghislain and his sister Aurore will receive a large inheritance from their recently deceased uncle Edouard only if they can prove their moral rectitude. But the nephew has a mistress, and the niece is a bit of a nymphomaniac. The behavior of the chauffeur, with the maid, tempts their employers into further indiscretions.