Yes, that is correct, Michael Mochan & Mary O'Donnell (married 6th Oct 1965) were the parents of 7 children that I am aware of - Helen Mochan m, Patrick Gallacher, Patrick Mochan m, Margaret Cardiff, Dennis Mochan m. Annie Harvey, Annie Mochan as you know m. Hugh Hamill, Thomas Mochan died in infancy, Mary Ann Mochan (my granny) m, Michael Joseph (Joe) Cuthbertson, & John Mochan had 2 marriages, 1st to Janet McDonach, (2 sons, James & Michael) and then to Catherine McGlinchey.
So your 3x grandmothers parents were Joseph Hamill (1827-1880)& Euphemia Simpson (1833-1899)- correct? That's as far back as I have gone with the Hamill's, the info was on Hugh Hamill / Annie Mochan marriage cert.