It appears that Mary Alice Birkett and her husband Andrew migrated to Brisbane Queensland in 1891 then it appears that Andrew Birkett committed suicide in 1905. I haven't found any children born to Mary and Andrew but am unable to access Qld BMD at moment so will double check. But as Mary's death notice didn't mention any children I would say they didn't have any.
The Brisbane Courier (Qld. : 1864 - 1933)Tuesday 26 September 1905
MACKAY. Sep. 25.--Andrew Birkett, a farmer near Homebush. committed suicide on Saturday .....you can see the rest of the story by going to Trove newspapers.