Hi there,
Just to follow up a little further, here is an example that may help explain how the ‘system’ worked in Dec 1916.
Among those who died while in the AIF was a young chap, Alfred Stanley ATKINS, 5970A, born Urunga NSW died in a Military Hospital at Fargo, (Wiltshire) England of Pneumonia at 1: 10 am 27 December 1916. His death was registered at Amesbury, Wiltshire, England, GRO ref Vol 5a, page 212, 4th Quarter 1916. His CWGC headstone is at the Durrington, Wiltshire cemetery, where there is a separate Memorial for the Australians.
His AIF service records cover some 41 pages (digitised, free to search online as per earlier link), and show that due to his illness, he never reached the FRONT, and the detailed records show the depth of details that AIF Base Records established and maintained. The file also shows that the Commanding Officer of that Military Hospital understood the AIF requirements (see the copy of the telegram he sent) and also the English civil law requirements. Among those military records is the Field Service Report that I mentioned earlier.
As far as I know, there was no NSW civil registration for his death.
I hope this information will help with the general question you are asking. I realise it is not for a Soldier who was injured or became ill at the Front and then was sent through to England. I am sorry I don't have an example at hand for that situation.
JM