I booked the following ticket:
Auckland-Queenstown
Queenstown-Hokitika
Hokitika-Auckland
It was all on the same PNR. I got the following SC:
Auckland-Queenstown 12
Queenstown-Christchurch 12
Christchurch-Hokitika 8
Hokitika-Christchurch 8
Christchurch-Auckland 12
I thought this was pretty good considering there was just a 2-hour layover in Christchurch each time.