Thomas Mellon and Mary Ann Fann did stay in Hamilton County. They are buried in Ten Mile Cemetery. However, they only had two sons (and three daughters) grow to adulthood. These sons seem to have had only daughters, so the family name did not continue. My great-grandmother was their granddaughter. I have information on the Mellons. Thomas H. Mellon was a Methodist preacher at Mellon's Chapel, now known by a different name. He was first cousin to Judge Thomas Mellon and is mentioned in Judge Mellon's family history.
However, I know very little about the Fanns.
Please email me at karsmith@yahoo.com and we can exchange information.