The Dexter children didn't travel to NZ with Jane and her husband, Charles. The only child they had with them was their own son, Samuel. I checked the passenger list of the ship they travelled on and there were no mention of any DEXTERS.
I will be looking more into the BOSS family (my husband's 3rd great-grandparents). If I manage to locate anything on the DEXTER's I will let you know.
-- Susan D'Ott
Perth, Western Australia