Found a Marriage certificate of John Harper McKnight, age 27, marrying Sarah Ann McDonald, age 20, in Kilwinning, Ayrshire on the 3rd April 1908. They were living at 9 Long Row, Fergushill, Kilwinning.
His father is noted as John Harper, mother noted as Mary Harper MS: McKnight. Could be she was married twice or she had John before being married...
Sarah's parents are noted as Stewart McDonald and Mary McDonald MS: Gartley.
Will check into my files to see if I can find more information.