Should I Tell Them?

I have had this dcg for about 4 months now. Dcg is almost 2 and we are entering "that" phase. I was sitting right by both of them today, baby in bouncer, when dcg walks up and tries to pinch baby, then a few minutes later, tries to hit baby. Of course I tell her "no, we don't hit" or pinch. I have not seen her do this before, but I am worried that it will get worse. She also threw a fit today and fell off of a little car toy outside, trapping one leg under it. I looked her over and she was fine, but this family is not the easiest to work with. Whenever I tell them ANYTHING but sunshine and roses, it's my fault. Even though they send her here with bruises (normal stuff for that age) and saying she was "having a really bad morning" meaning fit throwing. Should I tell them what's going on here and risk losing a client/being blamed for her behavior or should I just keep my mouth shut?