I go by the only invite as many children as the child is turning rule! That's what we have done. Other wise it's too overwhelming for both you and your DD! So aske her to name 4 friends, and they are the only people you invite. Unless you invite some of your own friends too, and they have children! For my DD's 4th bday, I had 4 friends from childcare, as well as 3 adult friends for me, lol! They brought their children, so it turned out there were about 9 kids all up. They had a blast and I wasn't overwhelmed trying to control and entertain them all.