When people die, the body is a shell, nothing more. They will remain for a few days to help and to say goodbye, then they return to their fuller spirit body, which has much more of their total being than the physical would ever hold. They'll only hang around graves when loved ones visit, to comfort, or because they can't move on for some reason. But as Spiritlite says... they'll be jumping up and down saying - Stop crying, I'm still alive!'