Hi

I need to book a DONE4 fairly urgently for a buisness trip as follows:

LHR-SIN-SYD-AKL-SYD-BNE-SYD-LAX-LHR

there is a small possibility that I may not need to make the day trip from SYD-BNE-SYD, but won't know this for a few days and need to book the ticket first. If I don't end up wanting to go to BNE, can I cancel those two flights, or do the fare rules mean I HAVE to travel to BNE rtn in order for my subsequent flights to remain valid? My reading of the fare rules suggests it is all quite flexible, but don't want to have to find I need to do a silly flight to BNE and back just for the sake of it!

Any assistance gratefully accepted!