What is a 'Party'?
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.