Does Demi have a secret half sister?

Every time we interview Demi Lovato, she always gushes about how close she is with her sisters Madison and Dallas. But in a recent interview, Demi revealed that there's yet another branch on the Lovato family tree! "I have an older half sister I've never known my whole life," Demi confesses. "I talked to her for the very first time around when I turned 20. She said she was waiting to see if I wanted a relationship, which I thought was so incredible." She's def a lucky girl to have someone as sweet you as a sister, Demi!