I do not know the answers to your questions, but there was a Hambleton Dogan in Hanover County, VA. on March 14, 1820 listed together on same date as Nathaniel Dogan. It appears that Nathaniel, Hambleton, David W. and James were brothers. Hambleton had a son named David Wade.It seems that likely the brothers were the sons of Timothy Dogan and Mary Wade. Your James A. could possibly be the son of either David or James. Nathaniel did not have a son named James.