No, this is not Eugenie (AKA Philosophy in the Bedroom). It’s also not Eugénie de Sade (AKA DeSade 2000). This is 1980’s Eugenie (Historia de una perversión), but yes, it’s another Jess Franco movie. It is a remake of the 1970 movie listed above and is also known as Erotismo. Franco danced with this subject many times, also making How to Seduce a Virgin.
Alberto de Rosa (Antonio Mayans, a Franco stock member) wants the young Eugenie (Katja Bienert, El tesoro de la diosa blanca), so he gets his sister Alba (Mabel Escano) to help by seducing her father and talking him into letting brother and sister take his daughter for, well, you can only guess.
Bienert is fine in this, but she’s also dealing with Maria Rohm and Soledad Miranda to live up to in Franco’s first two attempts. That’s not fair to her to be compared to them. She was also underage when this was made, which is something that would never happen today or at least we’d like to believe that.
This also has Lina Romay barking and behaving like a dog, so there’s that.
In Germany, most of the plot and character pieces are thrown away to make way for inserts from Triangle of Venus. For these Teutonic perverts, Jess Franco was simply not dirty enough.