Mike, Have you contacted the St. Charles Historical Museum, and possible the Elgin, Il Historical Museum. I checked " The Past and Present of Kane County " Pierce, Merrill, etc. (downloadable from Google Books as a PDF) It does't seem to have much about the GAR, but it does mention C T Elliott, John Elliott, Farnworth and possibly some other's of your family that I am not familiar with, may be worth a review for any clues that may help you find records. I am still trying to find those from Veteran GAR No. 49 from Elgin, IL.

as usual. Dan