As bookings tend to change in size, you may still want to keep them seated on the same table but increase/decrease the cover size.
This will let you keep your booking figures fully accurate but won't require any re-shuffling of your diary.
How to increase the cover size 'On the Fly'
This can be easily done however is only possible from within the grid view;
Click on the cover size box
Select the upwards or downwards arrows
Select the tick box
As this is a quick way to increase/decrease booking size without checking for availability, you might only want senior members of the team to be permitted to do this. You can change a user's permissions via settings - security and user permissions - user management - users:
Click setup against the user
In the first tab administrator privileges, untick override table/join capacity
If you wish the user to be given this privilege on the day of service only, tick allow to override table/join capacity on the current day only