I know this is a really old post but maybe someone out there still has an interest. I would like to share any info I can -- not that I have much on the Heffernan line.

My grandfather Thomas McCormick (born 1861 in Picton Ont Canada) married Ellen Bridget Heffernan (born 1860 in Picton Canada). From her death certificate, her parents were Thomas Heffernan and Bridget Coffey (other records and family knowledge refer to her mother as Mary.) We also have a (undocumented) story about a ship wreck on the way over from Ireland where a young son was wrapped in a blanket and all survived.

A newspaper article I found mentioned a brother of Ellen as Hugh Heffernan. While none of the children of Thomas and Bridget (Mary) match what you have listed, other facts seem to match. I have attempted to attach an image of the death certificate mentioned.

John McCormick (mccojr01@yahoo.com)