M.W.
I would definitely want to know the parents before allowing my daughter to spend the night. That said, the couple of times she's tried to spend the night away, I've ended up having to pick her up late when she decided she wanted to come home.
If you're up for it, I'd put on the invitation that the girls who aren't going to spend the whole night can still bring jammies to change into but can be picked up at 10pm (or whatever time you're comfortable with).