My son is having a birthday party in just over 2 weeks. Invites were sent out ages ago and the RSVP deadline on the invites was Jan 1st. Out of the almost 30 children we invited, only half have responded to the invite. This is our first time hosting a birthday party (he'll be 4). For those of you who have done this before, am I correct in thinking the people who have not responded are simply not going? Or should I make sure there's extra food in case anyone just turns up?