I had to change some of my reservations from 6 to 7 and viceversa, due to my MIL changing the dates she was joining us. The restaurants have different types of tables. Some are for 5 or 6, a few were for 6 or 7, some 7 or 8. When switching from 6 to 7 and back with the places we had a table for 6 or 7, all that the CM had to do was change the number of people on the reservation, everything else stayed the same. At the places that we had a table that seats 5 or 6 or 7 or 8, we had to cancel and make a whole new reservation. Most of the restaurants had tables for 5/6 and 7/8, so most of my reservations had to change (good news for you though since you are going from 5 to 6.) The only places I had tables for 6/7 were Jiko, Boma, and Princess Storybook. I'd call and change what I can and keep the ones I couldn't change and hope they will accomodate you when you arrive.