The Brides Wore Blood (1972)

The DeLorca family has been cursed ever since Carlos' grandfather was interrupted while conjuring evil spirits. The curse makes each DeLorca son turn into a vampire, and upon the birth of his succeeding son, the mother somehow dies. Carlos doesn't want to see that happen to his nephew Juan, who is beginning to show signs of the curse, so he consults a psychic medium, Madame von Kirst, who assures him that there is a way to end the curse. It involves luring four girls to the DeLorca house and performing an incantation.