Don't know if this will help but my great-aunt wrote that her aunt, Ann Brett, moved from Achonry, County Sligo to Canada with her sister, Susanna, and there married John Irwin. Susanna married William Knott. Their sister, Elizabeth Brett, my gg grandmother, married James Hammond and settled in Bolivar, PA. He and his brother Thomas owned brick yards there. 5 of the 7 brickyards in Bolivar were owned by Hammonds. I have some info re: the Bretts in County Sligo, but not much about those settling in Canada.