I wish it were a relationship. But my gggrandfather Robert married Jenny Graham. His son was Francis who married Mary Margaret Clark in Pettigo, Tyrone County, Northern Ireland. They immigrated in 1811 to the Port of New York in the ship West Point. That is most of the data I have on Robert except that he was probably a brother of Peter Johnston who was from Annandale Scotland, and was the grandfather of General Joseph Eggleston Johnston, who was famous during the Civil War on the Confederate side. Robert immigrated many years after Peter into the northern area of the USA, and so his descendants were Union advocates. But the relationship was known and admitted. Good luck. There sure are a lot of Johnstons, huh? Jeanne