Hi Carol,
I managed to find John Joseph Cain’s army record at www.archway.archives.govt.nz The document was approved to be placed online 5 June 2012 so I guess you don’t have this. You can download it from the site

Looking through it shows quite a lot of information :

Name : John Joseph Cain
Born : 10th March 1887
Father : James Cain – deceased
Mother : Margaret Cain

I was wrong about disembarking in Auckland he probably disembarked ship at Lyttelton, close to Christchurch, Canterbury. Arrived in NZ circa 1914
Worked as a farm labourer for the Wilson Brothers, Methven which is close to Christchurch, this was his last known NZ address.

Joined New Zealand Expeditionary Force 20th September 1917
Took the oath of allegiance in Featherston (North Island NZ ) 29 November 1917
Had resided in New Zealand for 3 years at this time

John died of a gunshot wound to the back which penetrated his abdomen.

He made a will which was left in his paybook . Will signed 28th March 1918 leaving his worldly possessions to his brother Richard Benjamin Cain who supposedly lived at Dunsandel (closer than Methven to Christchurch) but he couldn’t be found. Mrs Pennal name appears on first page of the service record – she resided in Ashburton, this is still in the Canterbury region ( google maps show proximity to each other)

Medal sent to mother Margaret Bridson (married again) ?
There are two addresses shown for Margaret - 30 Bucks Road, Douglas and 18 Richmond Grove.

I also found a Thomas Edward Cain from the IOM he married a NZ girl called Annie ? His son William James was born 19 April 1888 and was killed 6 February 1917. Records show his father lived in New Zealand 40 years +. I know the Cain name is prolific in the IOM maybe someone is looking for this relative.

Regards
Frank

There are lots more Cains on this site, unfortunately most you have to pay for - not WW1 service records. I'd recommend the site to anyone who had relatives who emigrated to New Zealand.