I am doing the same. Expect for me, I sound more like:

(while picking her up, to remove her from sitting on the babies backs)
No DCG, we dont sit on people. We need to be gentle.

OR

Off DCG. That is not where we sit.

But the second I put her down, she runs back to do the same behavior over. I have resorted to separating her to her highchair for a 'time out' because when she gets worked up she is either hurting herself or her friends.

I have talked to her mom about possibly checking her ears for two reasons. 1. She is not listening at all or acknowledging what I say. 2. She is very clumsy. She will be walking straight and drift off and bump straight into the wall. Or randomly trip over her feet. I cant help to think that it may have to do with coordination.