As many as you want. If you want everyone to come to the Hi Moms, then you have to pay 'x' amount of money per person which can get expensive if you want everyone to come to that as well. But for graduation, it doesn't matter. Just because you are limited to the number of invites that get sent out (2 or 3 I think), doesn't mean they need one to come see the graduation. No one pulls out a list when they show up to see if they are on it.