If you invited 30 or 40 people and some don't let you know that they're not coming, how do you plan for food?
If I had an informal invite to a picnic/party I would simply say, "Sure, we can make it. What would you like me to bring?" OR "Sorry, we already have plans for that day, but thanks for the invite."
It doesn't take but a second to say, YES or NO.
But if I had invited say 30-40 people to a picnic, I would simply plan on making enough food for 30-40 people whether they showed up or not. Then when you have a bunch of food leftover, just send some home with people. That's what I do.
If many people decide they don't want to bring any leftovers home, I would simply have another picnic the following day with some close friends/family.
This is what our good friends do that live across the street from us.
Every Memorial Day and July 4th, they throw a big picnic. There's usually 50-60 people or so that come throughout the day. And everyone brings something to eat. By the end of the day, there is usually quite a bit of food left. The following day they invite us over to have another cookout to use up the food. Actually, they don't even "invite" us anymore...it's just tradition that we show up the next day.
