Daughters of Darkness (1971)
AKA: Lèvres rouges, Les / Blood on the Lips / Blut an den Lippen / Children of the Night / Erzebeth / Rouge aux Lèvres, Le / The Promise of Red Lips / The Red Lips / The Redness / of the Lips / Vestale di Satana, La.
A 300-year-old lesbian vampire and her lover stay at a posh European resort. They seduce a sadistic husband and his beautiful wife. The husband is soon found dead, and his wife joins the two vampires.