SARA, There is no marriage listed in any state for Andrew under the spelling Rankmore but his children are listed as follows from the bdm index www.bdm.nsw.gov.au
Ansell born 1903 Dubbo
Adella b. 1898 Dubbo
Lila b. 1894 Warren
Herbert b. 1892 Dubbo
Emily b. 1884 Dubbo
no listing for Charles birth in n.s.w.
are you sure that he didn't marry in say england or elsewhere and come here after. Have you checked immigration records?