Dear kindertrauma,
Here is another old movie that I hope someone will recognize. There is a very pretty young lady (Miss Nywles) looking for her kin (I think, not sure) and she comes to an old house where she meets up with older witch types who tell her she is a descendant of the Selwyn family (the family name is turned around.) That is as much as I remember. The name has always stuck to my memories, so I know that part is true. I always got a chill watching the witches cast their spell with live pretty ladies.
Thanks,
saraeg
AUNT JOHN SEZ: Saraeg, the movie you are thinking of is 1960s THE CITY OF THE DEAD (a.k.a. HORROR HOTEL), which stars PATRICIA JESSEL as Elizabeth Selwyn, a witch burned at the stake in the 17th century who later returns as an inn keeper operating under the alias Mrs. Newless (Selwyn spoken backwards).
Speaking of backwards surnames, this Name That Trauma made me think of SUPER FRIENDS foil Mr. Mxyzptlk: