My son is turning 7 and as per his usual request, he wants a pool party. Last year was our first in the new house with a pool (pool party). What concerned me is that 2 sets of parents simply dropped their 3 children off (ironically, the non-swimmers) and left. With 10+ sugared up children in attendance & it being a pool party this really concerned me (Re: Safety!!). Fortunately, 2 older teenage brothers were recruited quickly as lifeguards.

How do I word it in the invitation (politely) to:
a) bring your own size appropriate flotation device if your child needs it and
b) stay with your non swimming children so I don't have to entertain them and watch the other swimmers too?!

This year I really limited it to 4 of his friends...but with siblings (how can I not include siblings?), the number is up to his 4 friends plus 5 younger siblings.