I have let my Ancestry sub lapse for the moment as I decided to pay for some certificates etc. so can no longer access your tree. I intend to take this up again in the future.
A few other avenues I am looking into are as follows -
we have a daughter living in the UK and she has connections with a researcher who is apparently willing to see what she can find - I have sent copies of George's marriage cert and some other bits and pieces; I have written to a family in Coen whose name appears as a witness on the same cert. This family still runs a business there. This was a week ago and I have not heard from them, and I may never do so, but here's hoping. As George was married in the Court House (which probably doesn't exist any more),I have wondered if there are any records which might indicate if John was alive at the time of George's marriage.
We are going to NSW in a few weeks time and intend to spend a day in Warwick and Stanthorpe to see if a personal visit will reveal any more clues.
Just as a matter of interest, on George's birth cert the provider of the info was Anne Jane and it appears she was illiterate - there is no signature, just her mark X. George's date of birth is May 24 1865.
I will certainly let you know when I have any further info