There is some dispute over the real authorship of the original book. Widely
attributed to Guy de Maupassant, the book looks to have been originally
published with the French title Les Cousines de la Colonelle, by Vicomtesse de
Coeur-Brûlant, possibly aka Madame de Mannoury aka Marquise de Mannoury
d'Ectot (according to the blurb on the book cover).
This is another erotic film from Swiss filmmaker Erwin C. Dietrich who specialises in this sort of countryside nude romp. If the film lacks a plot then this is more than compensated for by the amount of very attractive female flesh on display, which after all is what interests the viewers.
Karine Gambier plays the widowed Frau Oberst who likes to try out potential suitors for her two nieces played by Brigitte Lahaie and Pascale Vital but the nieces seem to have eyes only for each other, not that they are not interested in the guys but the guys seem a bit half-hearted in their attempts to make it with the girls. Still, never mind, with several girl/guy scenes they all come good (no pun intended) in the end.
One aspect of Mr Dietrich's filmmaking that I find interesting is his ability to secure picturesque locations such as castles and grand houses for his films. If this sort of film had been made in the UK, there would no doubt have been screaming headlines in the press calling for heads to roll and questions asked in Parliament but the Swiss and the continentals in general seem to take it all in their stride - and, in this reviewer's opinion, thank goodness for that.