I very much doubt it, else I'd have been aware of a connection between the families. I'd be surprised if members of the family never met or at least knew of each other back in Cornwall, but there's nothing to suggest the emigrants were friends to the degree they'd decided to emigrate together.
It might be that they didn't personally decide to emigrate to New Zealand together, but that they were recruited by the same firm of immigrant recruiters, trolling the area for likely candidates. Did a lot of families sudden turn up locally at the same time as your grandfather?
Here, in my father's hometown, (Nanaimo) a lot of the locals were recruited by the Hudson's Bay Company to work their new-found coal mines. So, they recruited from coal-mining towns in England. (Sadly, they hired guys who were used to working in mines, when what they should have brought over were workers skilled in starting mines, which is apparently a bit more technical than 'find coal face
Also, the company put the families up in the fort for a while, but then sent them forth to build their own houses: "But we're miners, dammit, Jim!"
The immigrants literally built this country.
On the other hand, somewhere between the tip of South America and Vancouver Island, my forefathers mutinied on board the ship that was bringing them to the new job. They were settled back down, but, way to go, Ancestors!