I thank you so much for your advice and I am going try that as well.
When my step-daughter was hitting children at school, I talked to her about it. She was in kindergarten. I said to her that one of these days you will hit the wrong girl. This girl will hit you back hard and hurt you. You will cry. She stopped after that exact thing happened at school. She took a Barbie away from another girl and the girl hit her and that was the end of her hitting at school.