Hi there,
Some New South Wales, Australia info:
NSW Electoral Roll, 1870 ARGYLE
John HUTCHINSON, residence, Kippilaw.
NSW ER 1878 ARGYLE
NO listing for anyone with surname HUTCHINSON.
So, it seems he had moved on by 1878.
Kippilaw is around 10 km west of Goulburn.
http://www.gundaroo.info/genealogy/cemeteries/kippilaw/kippilaw.htm http://www.gundaroo.info/genealogy/cemeteries/kippilaw/kippilaw.pdf Perhaps there’s a name there that may lead back to Ellen or her family.
Do you have Joseph's NSW birth cert (or official transcription) and if so, what info noted there ...?
Did Joseph marry in Australia, perhaps in NSW in 1906? What info is on that marriage cert (or official transcription) ?
I am happy to look through my NSW resources, just need some further clues

so I hope you don't mind my asking lots of questions.
Here's some more questions....
Re Joseph's mum .... What are the various documents that are giving you the alternative spellings of her name? Do you know if she was born NSW? Do you know where she died?
ADD
Could this be Joseph's birth registration?
The NSW BDM online index has a birth registered for a Joseph HUTCHINSON, with father as John and mother as Ellen. (#9566). The register’s entry should include details
that the informant provided as to where and when John and Ellen married, as well as Ellen’s nee name. The same number (#9566) at the index is also showing "NARVEN" for Joseph, and his father's name is not displayed. The surname for the CHILD was not actually a feature of NSW Birth registration certificates until very recent times (post 1975 from memory)
Civil Registration commences in NSW in March 1856, and births were recorded by deputy registrars receiving VERBAL advice from the informants until around WWI when the regulations were 'tightened'.
Cheers, JM