From the website I mentioned above...
"In 1858, in response to inter-tribal fighting, a detachment, commanded by Brevet Lieut. Col. Wyatt, was dispatched to Napier from Auckland, arriving 7 February on board the Eastfield, followed by three detachments from Wellington on the Wonga Wonga, arriving 26 February, 18 March and 25 March."
I wonder if Napier holds passenger lists for any of those voyages.
Have you eliminated a NZ marriage?
riley