Where are her parents?

They never explained in the sequel what happened to the older daughter, like if she was away at school or what, she was just gone and no one talked about her.

In this one, Carol Anne expresses missing her parents and Bruce mentions them calling, but what is the reason she is visiting these relatives and going to a special school, and not being close to her parents? You would think her parents, knowing how susceptible Carol Anne is to evil forces coming after her, would want
to keep her close to them?

Does anyone know why this is so?