I saw this movie on television about 1975. Two kids lived with an old lady could have been their grandmother. The little girl gets locked in a big doll house. Then there’s a scene in the back yard with a big haystack and someone gets killed on a pitch fork. And one of the kids gets their finger cut off and puts it in a box. Can’t remember if it was b&w or color.
Some of it sounds like The Other, but I don’t think s little girl is in it. It has the cut off finger in the box.
It is two identical twin boys.
sounds a bit like “Who Slew Auntie Roo?”
https://en.wikipedia.org/wiki/Whoever_Slew_Auntie_Roo%3F