I don't think anyone has tried this yet. If it's a dietary requirement, as in you are diabetic or something they would try to offer you a sugar free option for your dessert course.
Perhaps they might do it if your server is really nice, although the Dining Plan doesn't make allowances for such an instance at this time.
I read there will be changes coming May 31st.
Here is a quote from the article:
Guests who do not want a dessert will now have the ability to substitute that dessert choice for either a side salad, a cup of soup, or a fruit plate. Do keep in mind that this is only available upon request and substitutions may be limited. Guests will not be able to select an appetizer option instead.
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