Yes, if you have any of our payed plans you can import attendees to your guest list directly.
By clicking “Attendees” in the menu and then “Import/invite” and then choosing the "Skip invitation, just add to the attendee list". This means that these people will be marked as “Attending” and not "invited". You can import people one by one or choose to add a list of people at the same time. Remember to uncheck the box saying “Send confirmation email” (or "send ticket e-mail" if you have tickets) if you don’t want to send out confirmation emails.