It's definitely something I've considered, even more so when the only marriage record I could find that makes sense is John Jeffery and Susan Hanning. On John Walters' death certificate in 1912, Susan was the informant and it says their marriage was registered in Hammond Falts, NSW, her name listed as Susan Henney and that she was 33 years old when they were married. I can't find any actual record for that (which doesn't surprise me if she was married to John Jeffery previously).
The informant on Susan's death certificate was the matron and I'm afraid not as accurate - details don't match up as well.
Thank you for your suggestion, I will definitely explore these names as an option. If you happen to run into anything else please don't hesitate to share - your help and insight is much appreciated!!