I was thinking of you the last two days because I believe you have two sons that are 9 and 11 years old and it's my job (and joy) to keep an eye on and keep entertained two boys that are 12 and 13 years old., plus another pair of boys that are their friends. Their dad has non Hodgkin's lymphoma and went for some kind of treatment today.
It was my idea to let each of them bring a friend. So far it's been a no brainer because our house is pretty much the perfect place for a group of boys at almost any age to have fun on their own.
Today was their last day of school before Christmas, so they're innately happy to be done with school for a while.