Mary Mackay Morrison was the daughter of Samuel, of Geocrab, Harris, and his wife, Alexis Mackay, who were married in Harris in 1873 and emigrated to Marsboro, PQ, in 1877.

Mary was living in the Eastern Townships of Quebec when she met and married Murdo Macdonald, of Lake Megantic. Murdo had emigrated, from the cottars house at 37 North Tolsta, to Lake Megantic, while he was still a child.