141 pages of Edric Doyle KIDSON's military file may be viewed on-line at the National Archives of Australia.
Page 128 is a letter (1967) from Elizabeth, Edric's widow and next-of-kin as she describes herself. In it she states that she married William Charles NORDSVAN in 1920 (she doesn't say where). Looking at the NSW BMDs I see that the marriage was actually in 1919, in the Moree district of NSW, William C. NORDSVAN and Elizabeth B.B. KIDSON.
Also in the National Archives of Australia, but not on-line, are papers relating to Miles Sedgewick NORDSVAN, born 20th March 1916, London, England.
He served in the Second World War, rank of Captain, court-martial 1945. See also http://www.memorial....son.php?id=3625
There are two other Nordsvans on this memorial. One, I suspect to be Miles' brother (or half-brother) born in Moree 1918 (father William Nordsvan), the other Miles' son who served in Vietnam. At the NAA there's another NORDSVAN born in Moree in 1921 - another half-brother?
So one part of the story is true...I would guess that Miles' father was not a NORDSVAN, and that the boy adopted that name upon his mother's second marriage. However, I may be quite wrong in that respect.
The family is probably extant. It would be a simple matter for a direct descendant of Miles to apply for his service papers. They might hold something as yet unknown.