Looking for Descendants of David Mcdonald Mary Jane Smith of South Australia

Hi I am trying to find any descendants of David McDonald and Mary Jane Smith of South Australia.
They were married in 1868 and they had 7 children. David Edward B. B 1869, Charles Stewart B. 1871, John (Jack) Alexander B.1873, Albert Edgar B. 1876, Alan Christopher B. 1879 - D. 1882, Flora Beatrice B. 1882 and Violet Lily B. 1890.
Any help would be appreciated as I have hit the proverbial "brick wall".