Keep checking to see if a reservation for your whole group or for 1 or 2 at the same time opens up. If you find a reservation for 1 or 2, ask the castmembers at the podium if you can be seated together. There is no guarantee, but at least everyone will be seated.
Cancellations will occur, especially close to the day as park visitors change their plans and cancel to avoid the $10 per person penalty.
Walking up is a last resort because CP is usually fully booked and going from 6 to 7 you will need a larger table (an 8 top instead of a 6 top). Again, while castmembers will do their best, there is always the chance that one person in your group will have to find breakfast elsewhere. If the reservation is pre-park opening there is the possibility that one person will not be allowed in the park.