Great thread, this subject has been coming up in my house recently, so timing perfect.
I asked my lawyer about this stuff also and some of my thoughts below.
As for ownership of land, the wife still can own land, married or not, your surname or not.
Where the problem pops up is once the land department sees a foreign surname, it is entirely up to them, but by law they are obliged to investigate the situation, see recent Nation article below.
Now, this seems to be more in line with if you are going to be developing a block of land or a company is involved, but from all my feedback it is relevant for any land purchase.
I am reluctant to do it with my missus for this reason, we intend to buy and sell and build some more and I do not want the interrogation associated with it if we can get away with it by simply either not being married, or not registering it. After all we have been together for 11 years, in my view stronger than many formal marriages, certainly stronger than my previous one in Oz. But she does not see it that way….slap.
You will be asked to sign your life away re any dues to the land at the land office if a foreigner is involved through marriage. We have bought 2 blocks of land here and did not have to do this.
The other already mentioned point is the Will, is automatic if something happens by accident tomorrow, otherwise it goes to her family and not you if not married and no will.
Another point is responsibility for debt. My lawyer explained it like this…I had been previously told that you are 100% responsible for ALL debts incurred by your wife. This apparently is not true.
You are responsible for any debts incurred that are seen to be to the mutual benefit of yourself and or the family, children etc, not in-laws. For example, if she borrows money for gambling….then you are not responsible for that, no matter if borrowed from a shark or a bank against property etc. If she runs up a c/c buying crap of no benefit to you or children, you are not responsible. But if she spent half of that c/c bill on paying household bills etc, then you are responsible for half of it, or possibly all dependant on the courts decision as to who benefited most and probably who can afford to pay it back.
The other benefit is being able to borrow money together for a house or car etc. You cannot if not married, but you will be asked by the financial organization giving you the money to be solely responsible for it I believe, not 100% sure, but believe so.
Also as Ant mentioned, we have 2 kids with Oz citizenship and we did not have to show the mothers name as mine or marriage. Maybe kiwis are different like that…all the surnames sound the same…baaaaa
Re children and custody…I have not heard this so is of interest to me. However, I did go to family court a few years back and had my son recognized as legally mine. This was done for a vise purpose only. I use the documents every year in my application for visa and I should really get them translated one day to see exactly what they say. So I would wonder what would happen with my kids if what was quoted here is true, one being already recognized, the other not. I also believe it is greatly up to the courts decision and being a system where the judge is the oh wise one, up to him and I am told he goes by the simple fact of who can provide the best and secure home and future for the kids.