Now, the family has learnt their father and his friend, Bombardier Robert "Jock" White, who both have Otago connections, are to be honoured by having their names etched on a war memorial in the United States.
"It's a big surprise. It's amazing," Mr Don, of Wellington, said last night.
Sgt Don, whose family lived in the Kurow area for some time, and Jock White, who enlisted from Dunedin, were soldiers with the Royal New Zealand Army's 161 battery attached to the US Army's 173rd Airborne Brigade.
They died on September 14, 1965, when their vehicle, sixth in a convoy heading for the Viet Cong-held village of Ben Cat, was destroyed by a command-detonated mine. Sgt Don was 27 and Bdr White 28. Two passengers survived.
Now, their names, along with those of about 1750 Americans and 29 Australians killed while serving with the brigade, will be etched on a monument to be unveiled at the National Infantry Museum at Fort Benning, Georgia, on June 1.
Sgt Don's widow, Isabel Royal (76), who lives with Michael, said last night her husband was a professional soldier when she met him in the North Island in the 1960s. His parents, Jack and Betty, lived for some years in the Kurow area where Jack was a school teacher.
The couple adopted a son, Trevor, and had had Michael by the time Sgt Don was called up to go to Vietnam.
Mrs Royal, then a primary school teacher, lived for a time with other New Zealand army wives in Malacca, Malaysia, near the Terendak Camp where the 173rd Airborne was based.
She was back in New Zealand when she received news of her husband's death. Trevor was 5, Michael 1 and she was pregnant.
"We named [the baby] Alastair Mahara. Mahara means in memory of, so he was named in memory of his dad."
Mr Don said there were many tough times for his mother before she eventually remarried.
"War's not good on anyone. It's not good on families."
Bdr White left a widow, Poko and three young daughters, he said. He understood they lived in Auckland.
Attempts to contact Mrs White last night were unsuccessful.
Sgt Don and Bdr White were buried at Terendak Camp cemetery and both were posthumously awarded two South Vietnam Government awards, the Cross of Gallantry with Palm, and the Medal of Honour.
The family had been trying for years to have the bodies returned to New Zealand, Mr Don said.
About 150 New Zealanders served with the 173rd Airborne in 1965 and 1966, former RSA national president John Campbell, of Dunedin, said. After that time, the New Zealanders served with an Australian unit.
The memorial would be the first on US soil to include the names of New Zealanders and Australians, Mr Campbell, a Vietnam veteran, said.
"There is no greater honour. It is an acknowledgement that in Vietnam the New Zealanders, Australians and Americans were allies and that New Zealanders were an integral part of the 173rd."
He said moves were under way for Australian Vietnam veterans to attend the unveiling but he doubted if any New Zealanders would be there.
Chris Turver, of Kapiti, an NZPA journalist travelling with the New Zealand artillery forces, was moderately injured in the blast which killed the two men.
"It is a fitting tribute they are being honoured for their sacrifice."
In all, 37 New Zealand armed forces personnel died in Vietnam between 1965 and 1971.
