What is a 'Party' in relation to my guest list?

A simple way to think of a party is a group of guests that live at the same address or are closely linked in another one. For example, a family, a couple, or similar. It is important to note that one person from the party can RSVP for everyone else in that party.

Would you put these guests on the same invitation? Then it's a party. Do you want one of the guests to be able to RSVP for all of them? Put them in a party. 

The maximum party size is 15.