I do not know if this will help, but the mystery family of McDonald's came from Tiree. Donald (Daniel) McDonald and Flora McDonald were living in Kenovay, Tiree prior to the emigration. In fact John T. McDonald was baptized in Kenovay. So, a good place to start might be Tiree! I personally believe that Donald McDonald was from Caoles, Tiree prior to his marriage to Flora McDonald who was of Kenovay. I also have a working theory that Donald and Mary McDonald MacLean (Allan MacLean's wife - Baldoon Settlers) were siblings. And as such. Donald's mother also came to Canada (the Allan MacLean's mother in law of Selkirk's Letters/Diary).