Late 70s or 80s Movie

This may be a long shot, any help will be appreciated. I remember a movie, could have been made for TV. About two sisters. The younger sister thinks the neighbor is turning her sister into a witch. Her older sister is over there often and the younger sister spies. When she is caught the sister and old lady make her think she's crazy. That's all I can remember. It was kinda scary, but I was not a teen yet. Thanks in advance. I have looked pretty hard. I thought it was something like "My Sisters a Teenage Witch" but apparently not. ~Stacy