I believe that James married Mary's aunt Margaret and adopted Mary and brought her to Canada in 1911. I found a 1800's Scotland census with James McClelland listed as son in law to Thomas Grierson who was Margaret's father. I believe that Mary's mother was Jane Grierson, could not find out who her father was, but he must have had the last name Mills.
Have you taken a DNA test? If so, login to add it. If not, see our friends at Ancestry DNA.
James is 25 degrees from Emeril Lagasse, 23 degrees from Nigella Lawson, 26 degrees from Maggie Beer, 48 degrees from Mary Hunnings, 31 degrees from Joop Braakhekke, 29 degrees from Michael Chow, 28 degrees from Ree Drummond, 27 degrees from Paul Hollywood, 18 degrees from Matty Matheson, 27 degrees from Martha Stewart, 36 degrees from Danny Trejo and 32 degrees from Molly Yeh on our single family tree. Login to find your connection.
M > McClelland > James McClelland