The following marriages are in the Ontario marriage database:
William McDonald, 30 born Coldstream, Scotland, son of Robert McDonald and Agnes Pringle Kerr married Isabella Campell, 30, born Caithness, Scotland, daughter of George Campbell and Sophia Levach on 14 Oct 1896 in Toronto, York County, Ontario
Robert McDonald, 24, born Berwickshire, Scotland, son of Robert McDonald and Agnes P Kerr married Margaret E Clark, 31, born Manvers, daughter of James Clark and Sarah Fromey(?) on 19 Dec 1894 in Manvers Twp., Durham County, Ontario.
Robert McDonald, 46, born Coldstream, Scotland, son of Robert McDonald and Agnes Pringle Kerr married Jessie Anne Hastings, 31, born Metz Ontario, daughter of Alexander Hastings and Martha Henderson on 4 Dec 1918 in Woodstock, Oxford County, Ontario.
John Kerr McDonald, 40, Coldstream, Scotland, son of Robert McDonald and Agnes Kerr married Eliza Jane Irvine, 36, born Toronto, daughter of Gerald Irvine and Charlotte Crozier on 30 Mar 1915 in Erindale, Peel County, Ontario.
Agnes McDonald, 23, born Scotland, daughter of Robert McDonald and Agnes Care married William Steel, 35, born Scotland, son of John Steel and Mary McPherson on 29 Mar 1892 in Peterborough, Peterborough County, Ontario.
It seems likely that Agnes McDonald's mother was actually Kerr, not Care and her or William Steel's accent caused the misspelling.
Jacquie