I think it should be said that the Unitarian Univarsalist church is the one that Jasmine is involved with and is very accepting of polymary. Most other Christian churches are not at all accepting. I did a quick google search and there does seem to be a UU church in Auckland.
When I lived in Wellington I went to St Andrews on the Terrace, which is supposedly presbytarian but they call themselves 'rainbow' and they are about as accepting of diversity as you can get. I suppose this shows that there are liberal churches around but you have to hunt them out.