Since writing my last message I took a look at the IGI. Believe there was a brother Donald who also came to Canada.
The only family would appear to be:
Donald Mackay married Margaret Mackay on 7 Dec 1751 in Reay, Sutherland.
They had: John, born 17 July 1753; Angus, born 21 Sep 1755 and Donald, born 13 Sep 1757. All children born in Reay. Reay was partly in Sutherland and partly in Caithness. Mostly Mackays lived there. Many later moved down into Clyne and Kildonan.