Does the sister try to smother the brother with a pillow?

There was this movie I recall watching probably 15 years ago (I was about 6 or 7 maybe?) and there were two children, one a boy and the other a girl. If this movie was on network TV in 1992, it puts it very close to my memory range. The boy was tame (younger too I think) but the sister was crazy. She tried to kill the boy with a pillow and she battered him. I remember very odd scenes, something about pushing the kid down the stairs. The mother crouching next to the boy finding out he was being beat up or harmed by the girl. It was quite odd seeing it as a kid, given I was around the same age as the characters. I dont know why it even popped into my head, just thought someone here might know what I am writing about?