help to id 70's French film?

[tartancloak85]

The film I'd like to id is I believe French, from the early to mid 1970's. The story is about two women, I think sisters. The younger (18-20's?) is lusty and sexually active, the older (later 20's or 30's?) is the prim executive type, hair short or up in a bun. The scenes I recall include: opening, the younger sister has sex in an alley with a guy who dismounts a motorbike or motorcycle. Later she imagines sex with a guy in a white coat, I think her dentist or maybe a doctor.
An adult film actor drops off some film of one of his scenes. A woman working at the firm where he drops it off screens it, gets aroused and has sex with a guy in the screening room while the actor's film is running.
Near the end of the film, the younger sister attends a big party or picnic in the country. Meanwhile, the older sister has sex with several guys in a barn or farm cottage. She is reluctant at first but then is enthusiastic. Around this point there is a joke scene about a guy who is in danger of having anal sex forced upon him, who runs away.
I saw this is in a U.S. theatre in 1973 or 1974, as I recall, and have long
wanted to know the title, main actresses, and if it is available anywhere.
Many thanks for any help!

[beutelwolf]

sounds a bit like Delires Porno, but that was a bit later, 1977.

[tartancloak85]

Thanks beutelwolf! Perhaps that is the film. I will look for it.
I may be off in my recollection of the year of the film described, as I
am relying on memory of seeing it in a U.S. theatre over 30 years ago.