'Frankenstein all'italiana' (aka 'Casanova Frankenstein') 1975
Italian synopsis on
IMDB, translated into English via google translate:
"The professor Frankenstein returns to the castle with Countess Janet. During the wedding ceremony the Monster appears, which starts to decompose. With limbs remedied in bulk by Igor, the professor gives back life to the Creature, assisted in the enterprise by Alice and Maude. But the first, jealous of Janet, uses the monster's erotomanist tendencies to rape the girl, after being in turn a prey to the Creature. Frankenstein, having discovered the intrigue, decides to use the 'qualities' of the Creature for a transplant of genital organs; but the intervention fails. In the end, after having emasculated the professor and the Monster, Igor enjoys the three women"