Originally Posted by Thai-Kiwi

nzkarit is correct. NZ are quite particular about this on separate PNRs. I assume that adding AKL-CHC to the trip ex-SFO (which NZ would prefer you to do) was more expensive that buying a separate AKL-CHC-AKL (which can be much cheaper). Of course, you will know this means you carry all the risk for a mis-connect between the individual bookings.

So, you will need to collect bags from the domestic terminal on arrival at Auckland from your CHC-AKL flight, then walk (or free shuttle) to international terminal and check-in for your AKL-SFO flight. Very painless, except maybe for the check-in at AKL (if not in PE/J or not *G).