Hi there,
Are you only looking for the exact location of the gravesite for your gg grandmother's niece, or are you also seeking information about your gg grandmother? I ask because I have quite a number of offline NSW resources, particularly for the Western Division of NSW in the 19thC, as several of my ancestoral lines were up and down the Darling Back Blocks some were out there as drovers and shearers and Cobb and Co drivers, then there's several as Policemen, and court officials, errr for much of that century and into the 20thC .... Decades ago I had regular access to the hardcopy volumes of the Bourke & District Historic Society's papers. I now have the CD which is full of the 13 volumes of those papers, and is keyword searchable.
Sadly I can confirm that the various employee station records are not often found, perhaps because they were not needed to be kept in the same official way as say employee records are kept for various legal purposes today.
Also re unmarked graves ..... with the climatic conditions and the tyranny of distance factors, there's every reason to simply understand that a grave would have been dug, and a ceremony held, perhaps with the station owner or the most senior person present conducting the service,(Overseer or Superintendent or Manager). This does not suggest a lack of religion for the deceased, but simply that the distance to the nearest clergy may have been hundreds of miles TO him, and then hundreds of miles BACK with him and then the same distance twice more to take the clergyman back TO his home and for the person doing the fetching to return back to the station itself.
Sadly the practical issues would have been addressed ..... the ongoing health and hygiene of the community at the station would have been paramount and the burial would have been fairly soon after the death, which if sudden could well have been without any medico present.
I will have a quick look for your gg grandmother's second husband in case I can find some item of interest.
Many cheers, JM