The National Archives of Australia has a digital copy of a what appears to be a POW card for their son David Edward Duncan who was captured by the Japanese in WWII (if I'm reading this right).
The National Archives are at http://www.naa.gov.au.
In the top right hand corner of the page put in Malcolm McDonald Duncan and there will be 2 results in the search. The first is a work (published 1969) by Malcolm McDonald Duncan (son perhaps) and the second is digitized entry for David Edward Duncan. It's a 2 page card in English and what appears to be Japanese.
His father at that time was living in Bulimba in Qld.
http://www.ancestry.com.au has the Electoral Rolls available and you will most likely find the family there.
https://www.bdm.qld.gov.au/IndexSearch/queryEntry.m?type=deaths will let you order his death certificate and also that of Falconer who died in 1967.
It's very likely that the full death certificates will list the names of the children.