not strictly an aibu, but need quick advice.
My lovely CM looks after my DD a few times a week. Her DS is similar in age to my DD (just turned 2), and he has become quite aggressive over the last 6 months or so (hitting, shouting etc). CM has tried to deal with it as best she can, reinforcing no we don't hit, thinking step, removal of privileges etc. She has been open and honest about each time her DS has hit my DD, and has always been very apologetic. She tries to stay close to DD at all times to minimise these situations, but can't always be there in time.
Today she told me her DS bit my DD on the arm. DD cried at the time but was ok after a cuddle. 
We are moving to a new CM in September for various reasons, so this won't be a problem for much longer, but is there anything we both can do in the interim? < although resolving myself to the sad inevitability>