my father was a NZ'er in the 21st Battalion, so I have been down this route. If you have more information about him I suggest you write to >
Personnel Department Private Bag 905 Trentham Camp Upper Hutt New Zealand
Give as much information as you can (example below) and request his army records - you must explain your relationship, possibly send a copy of your birth cert. showing his name, this will then prove the relationship, you should then get copies of his records.
I also asked if my father had ever been awarded any medals and if so what they were - a short time later 5 medals turned up, awarded but never claimed, boy was I happy!
DoB : Enlisted at : Last NZ address : Next-of-kin : Army No. :
I also knew his Co. etc 'A' Company,21st Auckland Regiment,5th Brigade,2nd N.Z.E.F.