I know what happened to Mary McLaughlin, a daughter of Patrick McLaughlin and M. Heffran. She is my mother's grandmother. Mary McLoughlin Callahan had 12 children with her husband Thomas A. Callahan. They lived in many places along the route of the railroad system going west. Thomas was a railroad engineer. I know they lived in Morris, Minn, my grandfather Clayton Thomas Callahan was born there. They settled finally in Minot,ND where Thomas, who died in 1927 and Mary, who died in 1947(?)both are buried along with several of their children. Patrick and Margaret are my GGgrandparents on my mother's father's side.
I have been trying to find information on them and the callahan children for sometime now. Not much has surfaced, their names being so common for a Irishman.
I hope this reaches you after so many years since your posting about your McLaughlin ancesstor.