Her Wicked Ways (France 1979)

Marilyn Jess plays a young woman discovered by her aunt having sex with her boyfriend (Guy Royer) and sent off, for the correction of her wicked ways, to a house run by Monique Carrere with maid Brigitte Verbecq. Although they pretend to be strict, on her first night, Marilyn discovers Monique and Brigitte having lesbian sex and then joined by Robert Le Ray to make a threesome. Next day she looks for the dildo they used and is discovered by Monique discovers her using it on herself. Monique spanks Marilyn. Then Marilyn turns the tables and spanks Monique. They end up having g/g sex. Dominique Aveline has sex with Brigitte in the kichen and Marilyn spies on that too. Brigitte gets Marilyn to strip and tease Jacques Marbeuf and then Brigitte has sex with him. Monique invites Guy Royer to dinner and they have a threesome with Marilyn. Finally they all, plus Richard Lemieuvre, Céline Gallone, Lucie Doll and an unidentifed brunette have an orgy.