Yes and no You could definately book for one person on the future sailing and you will pay less deposit while onboard. Keep in mind that the $200 per person deposit is if you book through the group space we have secured. Rebooking onboard will fall under different deposit policies which is 20% of the cruise fare. DCL is currently running a promotion for rebooking while onboard where the deposit is half the normal amount - or 10% of the cruise fare. Again, I cannot guarantee this promotion will be in affect when we sail in December - it is up to Disney Cruise Line what promotions they want to run. Now - there are some factors to consider if you only book one passenger while onboard and decide to book more people later. First, only the people booked into your stateroom while onboard get the current rate. Additional passengers added after you return home will be at the current rate at the time you add them. Since pricing can increase as the ship fills you MAY wind up paying more for the people you add later than if you rebooking them while on the ship. Any onboard discounts will apply to new passengers added but the cruise fare could increase from the time you rebook onboard to the time you decide to add more people. In addition, as the ship fills there could be space issues and new guests may not be able to be added. Even if you book a stateroom category that can fit more people than what you book into that stateroom initially, factors such as life boat station capacities and childrens programming availabilities can restrict the addition of other passengers. You will need to weigh all these factors when deciding how/who you should rebook onboard.