I am trying to teach Hannah to be gentle when taking stuff from your hand (treats, toys, etc.). I will offer her a treat and tell her "be nice" and if she goes to grab it badly I will take it away and try agian until she does it how I think she should. It's the same way with her ball. I need to teach her how to be gentle because my sister in law may consider the way she grabs at treats and toys an aggressive act and not let her stay. Plus she will just walk up and grab whatever she wants out of my daughter's hand and often times she will catch my daughter's finger with her teeth (not bite but it still hurts).