Hi again...
Thanks for the reply.
The reason I asked for the parent's surname was because (as Ian pointed out) the surnames on the certificate are "farm names". There's often a good chance there would have been a patrynomic thrown in there too and I was thinking maybe the father Carl was using that in Dunedin. Might have given a clue to his origins but as it now seems the parents were not in Dunedin in 1885 (or possibly even in NZ) it looks like a bust :-)
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The reason I asked about the ITM was that a marriage certificate doesn't mention length of residence whereas an ITM does. It's often not all that helpful as the full description is something like
"Length of Residence in the registration district where the marriage is going to take place and not the actual length of time the bride and groom have been in NZ" 
Having said that, if John got off the boat in Dunedin in 1870 and never left Dunedin till his marriage in 1885 the ITM would say
"Length of Residence: 15 years" ... which would be really helpful to know.
One of the amazing things about Rootschat is that there are some very generous people kind enough to take photos on your behalf of ITM's or naturalisation papers (or anything else) when they visit the Archives. You may need to wait a week or two for your request to be filled but it's an awful lot cheaper than having Archives NZ charge you $50 an hour.
I would suggest you start a new thread entitled
"Wellington Archives look-up please" and ask for photos of the ITM and the naturalisation papers.
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Have you seen the 1905 death certifcate for John CARLSON. Although death certifcates are often inaccurate "Length of Residence" is one of the columns, as is "Birthplace". Might be worth $20.
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Where did you get the ~1848 birth date for Carl BJORNVIK mentioned in your original post. It would make Carl ~14 when his son John was born in ~1862, which seems fairly young.
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Register of NZ Finnshttp://maine.utu.fi/emregfree/nimihaku_e.phpYou may have more luck than me getting the above database to work. I keep getting a 500 error even though the other databases work fine. I suspect if John is mentioned it will just be a note saying that he was naturalised in 1902 so definitely not worth 20 euro.
Regards
Beg