The Vic Pioneer Index has Jno Deering born to Thos Deering and Jane Shields, registered at Chilwell (Geelong area) in 1859, registration no 13779. Is this the John you're looking for?
Eliza Deering was born to John Deering and Margaret Morris, registered in Ballarat in 1882, no 13703. Is this the first child?
And why is the marriage in Coolgardie incorrect? My grandparents married in Vic in Winslow and their 2nd child was born on the goldfields in WA. It's entirely possible for them to have travelled that distance since my folks did. My family followed the gold, no matter where it was. Other members of the family went from Vic to WA, worked the mines for a couple of years and went back to Vic. They always went by sea between either Albany or Fremantle and Warrnambool, Portland or Port Phillip. There was more travel than we realise between the east & west. We're so used to flying there.
Do you have the certificates for these? They are probably worth getting.
I'll get back to you later.