Are you sure about the parents of this particular Isaac Johnston, a carpenter & builder who lived in Linen Hall St & The Mall Armagh. I hadn't been able to find the mother's name myself. I only know that his father's name was William. Isaac had a brother Joseph Johnston also born in Tyrone in August 1863. Joseph enlisted in the RIC in Feb. 1882 and mainly served in Belfast. I calculated his age from his RIC service record. Joseph was married in March 1889 in Belfast to Elizabeth Drew. Isaac is the only sibling I'm sure about. Are all the siblings on this forum definite.