Hi SUSIEQ, Welcome to Cruise-Chat!
The largest tables they have are for 10. I'm sure they can work something out by pushing 2 smaller tables together or seating you side by side. If everyone is on the same booking they will know, if not have your Travel Agent or who ever you booked with cross-reference the bookings. I would also see the Maitre'D or Dining Room Manager as soon as possible after boarding.