Duct tape and Velcro wall. I think every daycare should have those things
I kid of course
Do you have a stroller with a 5point harness. I know they can rock it and try and tip it over but wedge it close to the wall maybe? Just till you get a high chair maybe? I don't know really. I have a Maclaren that has a harness in it that my kid couldn't undo but some others maybe quick to learn.
GOOD LUCK!