Hi there, Charles!
I happen to know the answer to this question from my own experience. I had made some plans for my nieces and nephews but when my sister went to take them to the parks, she couldn't see them at all!
It turns out that a minor's account is unable to be shared between adult
My Disney Experience Accounts. To get around this issue, you have two options.
Your first option is if your child creates a new account for your grandson in their My Disney Experience Account. This approach works best if you do not need to access anything like
existing tickets.
If you do need to access existing tickets, you will need to call
(407) 939-4357 and the friendly Website Support Cast Members will move your grandson from your profile to your child's profile.
I hope that this helped, Charles!
Happy Planning!
Sarah B.