Thank Matthew - I did drive by that Stonehaven address and it is a now a block of units -there is reference to Stonehaven possibly being a private hospital back in the day (though not confirmed) so I wondered if she worked there as a nurse - or was she a patient there as this coincides with the years after the baby's birth and immediately before she 'disappears'
We have looked for her dying, going to NZ, marrying, moving interstate, going to War - nothing has come up, but then again, we may have missed it.
I think the Benett is actually a misprint - if you write Brett by longhand, you can possibly see Benett so I think this is the same person.