Ex-navy officer Wayne Williams, 62, said the ceremony was important to keep the memory of his late brother, Corporal Jack Williams, alive.
"His unit still have reunions every year or two, and they always invite the family along."
Corporal Williams volunteered to demote to Private in 1968 so he could serve in Vietnam.
"He broke his leg in Burnham, but covered it up so he could go train in Malaysia," says his brother.
"He had a broken leg, but he passed the fitness test anyway."
Williams was then deployed to Vietnam in 1969, where he was killed in action on June 16.
His niece, Amber Uren, said: "It's wonderful for him to have recognition after so many years."
Since April last year, more than 33,000 NZDSM medals have been issued.
A second ceremony will be held today at Christchurch's Royal NZ Air Force Museum at Wigram.
HONOURED
The list of service personnel recognised:
* CPO Manu Aranga
* GNR Barry Brett
* CPL Walter Joseph Callis
* WREN Denise Cameron
* PTE Douglas Arthur Campbell
* GNR Neil Henry Evans
* PTE Alan Herbert Fenton
* CAPT Troy Fisher
* DVR Jack Edward Goodwin
* T/CPL Rodney Boyd Jones
* CFN Graeme Lynch
* LT COL Edward Marr
* T/SGT James Marr
* W/O James Slaven Muir
* CPL John Stewart Williams
* POWM Alan Wingrove