You have to look at the keeping her separate as a learning time for her not a punishment. If we don't play nice with our friends we don't play with them period. I have a tendency to just do things my own way and leave the parents out of it. If you tell them you are going to isolate their child till she smartens up and acts properly it isn't going to go over well but/...... the other options aren't going to go over well either if they have to leave care. What goes on at home the parents deal with in their way. What goes on at daycare I deal with in my way. If what I do has no effect and I see no other options then parent can be told look I tried a zillion things and it is getting no better so you are gone.
In this case I think a lot will get better as the child gets older and more verbal and develops some actual play skills but right now needs to learn that no means no and you get separated every time.