We require an RSVP through Partiful to register a guest for the event, unless they’re added as someone’s +1!
If you invite guests directly through Partiful, they'll show up on your Guest List as "Invited," and then you'll be able to manually modify their response as long as they have an existing Partiful account! You'll also be able to send them text blasts.
To invite guests through Partiful, you can either sync your contacts or invite mutuals by filtering by past events that you've attended or hosted. You can do this by clicking "Invite" on your event page, and then clicking the filter button in the top right corner to see event options.