Stephanie:
I have eaten at Chef Mickey's with the last breakfast seating of the day and found the characters to be there until we left, in fact a good hour after the restaurant officially closed. Although it was a
different restaurant, we found this scenario gave us more than enough time for pictures with fewer diners. I would imagine you might find the same at
Cinderella's Royal Table. Unlike other restaurants where you could simply order dessert off the menu or a late-night snack to fit a late seating, CRT has one price for the meal. Added to the fact that you no longer receive your picture with Cinderella for free but through
PhotoPass, the additional cost of the picture might be the last straw to an expensive dinner so late at night.
However, you're paying for the experience. The opportunity to meet several princesses in one of the most magical settings on property and possibly with fewer children at this later seating can absolutely be a grand birthday. Additionally, let me recommend that you email the Special Events team at the restaurant to discuss their Princess Package and get other insight into making a late-night seating special for her. They can be reached at wdw.crt.special.events@disney.com
Wishing y'all a magical vacation!
Whitney