I'm trying to identify an old, obscure horror movie. A rich landholder adopts and then kills gypsy children to give himself immortality. Two of the children, brother and sister, return to haunt him, ultimately to his death. In one of the final scenes the two dead (and grossly green) children pursue him, arms outstretched, hideously long curled fingernails reaching for him, while the boy plays an accordion. They are singing. Can anyone help please?
You can see the dead boy and girl in the clip below; they have bluish\green skin and long fingernails, and the boy plays a hurdy-gurdy (I think they also sing around the house):
It turns out the old cousin had burned their hearts and drank the ashes to be immortal, but in the end, the 2 ghost children avenge their deaths by ripping out his heart.