Hey there, hi there, Karen! Welcome, and thank you for the question.
Every guest entering a
Walt Disney World theme park is going to need a
theme park reservation in order to go. There also may be different availability based on the
type of ticket you have. So in the case of your grandson, who has the
Sorcerers Pass, there may be open reservations for his pass and not for your son's pass.
I checked the calendar myself just now, and there aren't any days that are totally full, so I have a suggestion. Your son has the
park hopper option on his pass, so my suggestion would be that they make a reservation for any of the parks that currently have availability, and then at 2 PM, they can hop over to the park they prefer to be enjoying. They do need to "swipe in" at the theme park where they have their reservation, but after 2 PM, they are free to roam to any of the other theme parks.
Another option is to just keep checking. I've been able to score theme park reservations on the day that I was hoping to visit, even though they had been fully booked. There are often cancellations that would open up space for your guys to go. I recommend checking the availability calendar at least a couple of times a day, but especially in the morning and late in the evening.
My fingers are crossed, and I'm sending you a boatload of virtual pixie dust in hopes this all works out.
Anna