Keep families and friends together, and let one person RSVP for the group.
Groups tie related guests together — a family, a couple, a table of work friends. Seating uses them to keep people who belong together, together.
Where groups come from
If your spreadsheet had a family or group column, Vesavo creates those groups for you during import. You can also create and edit groups by hand at any time.

Shared RSVPs
Turn on shared RSVPs for a group and any member can respond on behalf of everyone in it — ideal for families. Leave it off for friend groups, where each person responds for themselves.
Plus-ones
You can let guests bring a plus-one. When they RSVP, they add their plus-one's name themselves, so you don't have to chase the details.
When Shared RSVP is on, the number of plus-ones allowed is for the group as a whole. When Shared RSVP is off, the number of plus-ones allowed is for each guest.
For example, if you are inviting a family and only know the names of the parents and know they have 3 children, you can add 3 plus-ones to the family group with Shared RSVP on. This will also give the option of the parents choosing if they wish to bring their children.
If the number of plus-ones allowed for a group or individual is lowered after they have RSVPd and added a plus-one, existing plus-ones will not be affected, even if the number of plus-ones added by the guest is higher than the new allowed value.
Groups are about who's related; functions are about who's invited to what. They're separate — a guest is in one group, but can be invited to several functions.