Does anyone know how the Johnsons, Gatlins and particuarly the Daughertys are related?

I'm a descendant, I believe, of Richard Johnson (1730-1796), brother of Elizabeth Johnson who was the wife of Captain Edward Gatlin. In Richard's will he bequeaths something to his nephew, Richard Johnson Daugherty. Ancestry says that Owen Daugherty (1740-1785) is a common ancestor of our Johnson line and the Daugherty line, and Elizabeth Johnson's mother is a common ancestor to our Johnson line and the Gatlin line. Was Richard's wife a Daugherty? How is Richard Johnson Daugherty his nephew? Did Richard Johnson (1730-1796) have kids? Why did he not leave anything to any kids in his will? Thanks.