By adoption, I too am related to General John Coffee. My adopted grandmother (Mae O. Coffee) was either the daughter or grand daughter to the General.
She married Harris Homer Mickel, which my adopted father (John Coffee Mickel) was one of the sons of that marriage. Mae Coffee Mickel died in 1974. I have a picture of her, taken about 1959 - 60).
I have just begun my search on these roots, and would appreciate anything you find, if this lead helps you to find anything more.