My DD wants a science party for her 7th birthday...it looks great so I've called them and checked availability etc, and they've said it's max 30. I asked if I invited the whole class (30), and they all came, does that mean my DD's little sister couldn't watch... and apparently it does! 
So I thought I'll have to invite less. I've always done whole class parties before and also invited a few girls who used to be in the class but now go to a different school...so I thought I could include them, DD's sister, and that would leave me with 22 kids.
But that just seems mean!
WWYD?