Here's a little spoke in the proverbial for you:
The marriage of the parents?
2678/1860 William Haley to Mercy Thompson in Tumut.
Do note mother's surname.
With the first child being born in 1861 it is possible that these are the folks.
No marriage for a Mercy Walters to anyone, but there are two Sophia Walters. Not until '71 and '86, though.
You can access the catholic search wia Rookwood's site, too.
http://www.rookwoodcemetery.com.auUnfortunately the Anglican records aren't online, yet.
There is also a CD for South Head. A chatter may have it. You could post new requests for cemetery CD lookups.
If you get the cert for either John or Sophia, it would indicate where they are buried, I think.
Jamjar