My G-Grandfather John Cassidy had a brother James Henry whose birth on 4 May 1877 was recorded at Clonroot, Richill, Co Armagh. Their parents were Joseph and Rebecca who were married at Kilmore Church of Ireland in 1872 (Joseph was a widower so may have had another family with his first wife).
If your James was CoI then there may be a link as very few Cassidy families listed on the Irish Census were CoI.
I've very little info about John apart from he brought his wife & daughter (my Gran) to Scotland c1907 but he disappeared out of my Gran's life a few years after her Mum died (believed to have gone to England), he was thought to have been in the army during Boer War but so far not found anything between his birth in 1879 and getting married in 1905, he was on Scottish Census 1911.
