I read this last night, but had to take some time to ponder a "solution," if you will. With 9 adults & 1 child in tow, I believe your grand-DD is going to get spoiled (in a good way)! "Oooh, try this ______(insert name)! Let me get you this ______(insert name)! You want to get a pearl from Japan, you got it _____(insert name)!" (sorry, the last one is a bit of a curve ball...it's what I do every time we go to EP
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Before you go, you could print out, or simply peruse, the F&W menus. Make a little pamphlet or "menu" of your very own, with certain items highlighted that she'd really, really like to try. Another fun thing at EP, buy a Disney passport and stop in at the KidCot stations throughout Worldshowcase, where it will be signed and stamped in that countries' native language! (My oldest DD LOVED this: when we got home, I put a picture of her in the front, along with her name, tagged one page, taught her how to say, "Hi" in that language, and then she took it to school for a show-and-tell.)
As for riding rides, ask her before you leave: "Is there anything that you really want to ride?" Then explain that you're going with other adults (does she know any of the them?), so she's going to experience newer things, be it food or attractions, at WDW! Maybe surprise her with MNSSHP! At the end of the trip, if your pocket allows this, let her pick out a pin or trinket to commemorate this solo trip (but, you might want to get her siblings something as well, if she has any; my kids go bezurk if one gets something and the other does not, & they're 6 & 3).
As you realize, you will probably have to slow things down in order for your grand-DD to keep up with the group; take mid-day siestas or find a bench in the shade to rest. Kids need down-time as much as adults; my kids enjoy just running about or hitting up a playground. If you find your grand-DD starting to wear, rent a stroller from one of the parks. In all honesty though, you know yourself and grand-DD best....sooooo, do what feels right to you.
Enjoy your culinary experience!!!