What is this movie I'm remembering?

I think this was a TV movie from the 80s but it may have come out in
theaters. I saw it on TV in the early 90s.

It is basically about a family and I think they have four kids. The
two older kids are bad or at least the parents think they are bad and
make them live out in a shed or something in the backyard with a
barbed wire fence or a fence made out of barbed wire going around it
or something. I think there is a skull and cross bone sign on the
fenced made out of barbed wire.

I think the two older kids are a boy and a girl.

In one part I remember one of the younger kids waves or something to
one of the older kids and one of the parents tell the younger kid to
get away from there.

Near the end of the movie I think the two older kids get out and I
guess it turns out the parents are crazy and they try to hunt down the
kids in the house. I think the dad chases them with an axe.

I'm not real sure but I believe it was based off a true story because
at the end of the movie it tells what happened to the kids.

The older two kids are like teens while the younger ones are around
probably 8 and 9.

Does anyone know what I'm talking about?
@Crystal Glass No that's not it but thanks for answering. I don't
believe it is a horror movie but more of a suspense movie. I don't
think there is any haunting or priests in it but I'm not sure. It's
been years since i've seen it and I only saw it once.
The only other movie I can really compare it to is "Flowers in the
Attic" which has somewhat of a similar theme although I'm not sure
because I don't know the whole plot of the movie I'm trying to find.