There may be another way of possibly tracing descendants of some Australian WW1 veterans,
You may already have heard of the Ryerson index http://www.rootsweb....sdps/papers.htm
(This is an index for searching some Australian death/probate notices, if the death was in Australia and a death notice was published.)
It has volunteers updating this site with recent burtial/probate notices from the mainly NSW papers in Australia, but is is increasing its coverage of Australian papers and this index is linked to other sites that search other Australian newspapers.
Assuming that the person died in Australia, you could search this index and you may be lucky enough to find a death notice that gives information about where the person lived, their age and perhaps other family members.
If you also use the births, deaths and marriages online sites for the specific Australian state you are interested in, you may be able to use both the Ryerson index and the information from past births, deaths.
The Ryerson index only mentions the date and which paper these articles are listed in and a very brief summary, but you can then search in perhaps the Australian National Library, or a larger state library, probably on their newspaper microfiche sections, unless the specific paper and dates you are interested is an Australian paper that has been digitised and is to be found online in the old newspaper section of the National Library of Australia site.
I hope the above information is useful in trying to trace descendants of some Australian WW1 veterans. Regards, Sandra