I'm guessing it's late 70s/early 80s, probably French, set in a mansion. One scene that sticks in the mind is when one of the girls, a blonde, learns that her father is having sex with the maid and she visits him instead of the maid in the dark, halfway through the sex he switches on the light but they continue having sex, unfortunately there is loud music drowning out the sound.
Can anyone put a name to this movie or give a guess, I've already tried a few of the Alpha France films with no luck.