Brilliant find CupofLife.
So now we have a possible indicator that Russell and Margaret were in Wilcannia in 1888. The obit for their daughter Bertha (Mother M Elizabeth) gives her birthplace as Wilcannia abt 1886. As well as that there's the use of the forename Herbert for this deceased child (presumably a child) which is a possible link to "Russell MIDLANE"s former identity. None of the surnames or forenames are particularly common which, at least, makes the theory plausible.
Cando, I'd buy the certificates myself but one in SA and one in NSW and all you get is a transcription which is nowhere near as helpful. I meant to thank you for the link to the obit as well .
Judith