Yana Nirvana, Marilyn Corwin & Jennifer Stace were all members of the LA Knockers, an all-female dance troupe that appeared in a variety of film and TV projects between 1974-1986.
The stepmother's song "It's So Hard to Find a Man," which she performed while ogling men at The Royal Ball, was included on Lightning Video's 1987 VHS release (and it was featured in cable TV airings from the same era), but it's missing from all DVD, Blu-Ray, and streaming versions of the film.