The marriage record, 1889, Albert G DONNELLY and Ada MANSFIELD. is the earliest evidence you have that your ancestor existed?
In researching his origins, you need to see this record. You need to see information that he gives about himself, by himself.
The Burrowa News 1 Jul 1938 p7
https://trove.nla.gov.au/newspaper/article/102500499?...obituary for Albert George DONNELLY....72 years old...only son of the late Christopher DONNELLY of Yass where he (Albert) was born.....
This is information about your Albert George, presented after his death. This would be information gathered by his family while he was alive, with Albert as the source.
Using NSW BDM index I see three sons to Albert George DONNELLY and Ada. Albert George, the only son of Christopher, does not give that name to a son?.......... worth noting.
The information on BDM certificates is important for your research. You need to list the information...all in one place...… Giving fragmented details over these numerous posts is inefficient, and difficult to use as reference material. You need to list the contents of certificates.
Can you please list the details on the certificates that you have, and also get the marriage certificate for your ancestor, Albert George DONNELLY, 1889.