Hi Susan.
With updates to the online dining system having recently taken place, many dining locations now require a credit guarantee or in some cases, prepayment up front. Of course, the prepayment does not apply if you have purchased a Disney Dining Plan with your Magic Your Way package.
I've just spoken to a Cast Member at Disney Dining on your behalf to inquire about the process since these changes have taken place. Since you're on the
Disney Dining Plan, your credit card would be used as a guarantee only (charged only if you do not show for your reservation). To ensure this is processed correctly, you need to make sure that you have signed in to your Resort Reservation package through the Walt Disney World system before you enter the dining reservations online system.
To avoid any unnecessary charges, I would highly recommend that in the case of a 'pre-paid' reservation such as
Cinderella's Royal Table, your best route would be to call Disney Dining Reservations directly at (407) WDW-DINE where a Cast Member will be able to book your requested reservation for you and set you up with a credit card guarantee - notating your Resort Stay and Dining Plan information - with NO charges made to your card. When you arrive for your reservation, the host/hostess and server will confirm your Dining Plan also.
Even though you won't book the reservation online, it will still be linked to your resort stay and you'll be able to print it out with your others while logged into your resort reservation.
Wishing you a Magical evening dining with Cinderella and a wonderful time at Walt Disney World!
Kirsten