Most of my family migrated from Maryland to SC to Georgia. I know there were several Cofer brothers or cousins that also went to Virginia.
I am not sure if this is a clue that will help or not, but I have a Thomas Cofer listed in "The Wilkes County Papers" (in GA) in 1831 that shows three children, Martha, Ann and John. They are 16, 12 and 14 in 1831. The age takes them back to about the time you were looking for James Thomas or Joseph. I know these may not be the ones, but perhaps it is a lead. I would be interested in staying in touch as I still have some needs to confirm some of my line in the late 1700's. Feel free to contact me directly at
debsc@computron.net