I am trying to find out what happened to my 2x great grandmother's sister, Catherine Driscoll, and her family.

Catherine Driscoll married Frederick Behrens (recorded as Behrins) at Sydney on 3 August, 1865. The couple appear to have had only 1 child named Mary who was born in 1866 but died in 1867. Death notices for the child were published in the SMH and that is the last trace I can find for this family. Does anyone have any ideas on what became of Frederick and Catherine?