Girl In My House

I know this may sound like a ghost story. But I swear it's real. A little girl died in my house back in the 60's (Rebecka), and she doesn't realize she is dead. My little sister whom is 5 has been living in her room and the child has become angry. My sister will fall as if she has been tripped and she would scream "She hurt me!". Yet no one is there. Also something will take her toys, her TV stopped working, And every time I walk in something always goes on. I never liked that room it made me feel off the second we moved in. After awhile my sister started drawing signs that didn't make sense to me. So me and my best friend Brit looked it and up turns out its demonic. But why would a ghost that is about nine years old have something do with any demonic. But for as long as I could remember I saw things, heard things, feel things, and My sister has all the things I have. It's not fair that things try and hurt her and come after her like they have been around me at a young age. I know there is more things out there and now one is in my house. Sometimes when I walk into my sisters room she seems to just be playing with dolls. But more so she is starring I'll call her name and she won't move. Doesn't even blink. Then I call her the little girl's name Rebecka and my sister snaps out of it. I have see this girl in the hallway at the both room door. And so many other places. She will change radio stations. I have made a spirit bag to contain what ever it is it seems to be working. But I know this is more than a little girl in my house any ideas?