Hi Dave, is the Sellars whanau that you are looking for have connection to Captain Daniel Sellars of Tauranga District who was born in Scotland March 1830-arrived in New Zealand 1855 or 1856. I have some information on that Maori line.
From what i know my Great Grand father came from Ireland to Aus with the prisoners from England and then come on to NZ to work on a farm in Howick. My grand was born in Napier and went to SA before the first world war and never came back to NZ.
I would be happy if you can help me as i have heard that we maay be from Maori family.