Hi, Dorothy!
There are a few options for you to make sure you have what your grandkids need. You'll find conveniences right on property, and you'll have easy access to taxis, Uber, and Lyft if there's anything you can't find right at your resort.
There is some
grocery delivery available right there at
Disney's Saratoga Springs Resort and Spa. You can place the order before you arrive, and the groceries are delivered to your resort room after you check in. If you're not there, they will put perishables away for you.
There are also other services, such as Garden Grocer, that will deliver your groceries right to your resort. You can do a web search for these companies, but I can personally say that Garden Grocer has been a great way for us to save a trip to the grocery store. They have a good selection of fresh food options available, and you can usually get things like the individually packed sliced apples, baby carrots, and cherry tomatoes, which make great things to pack for the park.
One more thing -
The Artist's Palette, located right there at your resort, will have some options for fruit and veggies. There are freshly made salads, cut fruit, and whole fruit readily available to grab as you need.
Have faith also in the culinary teams at Walt Disney World. They are phenomenal with
special dietary requests.
Enjoy your visit!
Anna