Hi dfc,
Now, don't panic, I am not advocating you spend up on more NSW certs/transcriptions but ...
Have you considered following up on ALL HEFFERNAN on the NSW ER as eligible to vote at Trangie in Dec 1903?
To save others going back of the thread
NSW ER 1903 ROBERTSON polling at Trangie (eligible to vote : 21 and over, and British Subjects)
Ada HEFFERNAN, of Trangie, domestic duties
Michael HEFFERNAN of Trangie, labourer
Patrick HEFFERNAN of Trangie, engine-driver
Thomas HEFFERNAN of Trangie, hotel-keeper
So I wonder about Michael

I can see a Michael HEFFERNAN, 17 May 1912, in a spot of bother at the NSW SR index…. He was at Nymagee … And from the NSW Police Gazettes “First Offenders Discharged …. Michael HEFFERNAN, (70) tried at Dubbo Quarter Sessions sheep stealing… So that chap was 70 years of age. I wonder if he was the father/uncle/cousin/or otherwise related to Thomas the hotel keeper?
And then there’s the following
NSW ER 1903 MACQUARIE, polling at Wallerawang
James HEFFERNAN, of Wallerawang, railway fireman
Lucy HEFFERNAN of Wallerawang, domestic duties
Could this be part of the same Heffernan family as Patrick ? (Yes, I checked the Portland polling place too, NO sightings of Heffernan ....

he is elusive

and Nymagee .... NO sightings of Heffernan )
Cheers, JM