Wonder if it is supernatural or she's Schizophrenic. As the voices tell you to do stuff exactly like she's hearing. Esp to hurt others. But being believed would make them go. For now.... If its a genuine ghost. He was definitely giving your sister some mental abuse. Feeling all alone. Isolating her and what not. Wonder if those numbers fucked him up. Those that seek power are usually succumbed by it and can't handle it at all.