familysearch.org shows a daughter, Katherine Syme born 30 Jan 1732 at Dunning, Perthshire, Scotland. Parents are David Syme and Katherine Chapman.
A sons, David Syme born 21 Apr 1734 and Andrew Syme born 10 Feb 1745. Son William's christening is 7 Jun 1749. Son John christened on the same day as William.
Other children include Jean, James, Helen, and Thomas 20 Jun 1736 christening.