Horror 70s or 80's Hear's voices?


Sorry for vauge title. I'm trying to remember a movie I believe was late 70s possible 80's.

I could be a classic but I'm not very good in horrors.

All I remember is a family and either a young female early teens is hearing voices. Her brother might be the crazy one. Im not sure. Strange thing is I think I remember in one scenes she wearing a striped green and white shirt.

I'm not sure if this is enough info. When I was a kid I was scared silly so I kept my eyes closed threw most of it.

Any help would be great.

Was this a supernatural thriller (e.g., ghost, possession, etc.), slasher (e.g., brother is psycho killer) or other type of horror movie? Do you remember any more of what anybody looked like?
"You seem a decent fellow. I hate to kill you."
"You seem a decent fellow. I hate to die."

I think the 2nd choice.

That elusive hide-and-seek cow is at it again
I'm pretty sure this is NOT your movie, but I need to post this trailer here anyway. Because I need to. Actually, I did think of this because of the bro/sis relationship and the green and stripes reference. But still, doubt it's going to help.

Little known movie trivia FACT: this is the Harry Potter origins story line. >=]