As I was changing my Air Newzealand flights yesterday (before find UA flights today) I also seem to have discovered that since I was flying SFO-LAX-(AKL)-MEL-(AKL)-LAX-SFO that since it was a mixture of carriers when she put in to search all availability for MEL-(AKL)-LAX-SFO it didn't come up with anything in business class. However when she broke it down to MEL-(AKL)-LAX it showed business class available and then she added on the LAX-SFO in economy.