Can you change the date of a flight on a Qantas OneWorld RTW redemption?

Help… Can anyone reveal how they have gone with changing a OneWorld RTW trip. When booked we took roughly any dates we could get but now I found our “same” flights out 3 days earlier which is what we wanted.
I rang Hobart today but they advised they would have to cancel whole trip to reticket and there was a real risk I could loose all my other legs if some other agent swooped in and took them. I just cannot believe they cannot somehow ‘hold’ my current bookings during this process. I said nope can’t risk that!

I would try calling again. I’ve changed flights on a Oneworld Award previously without having to cancel other flights on the booking. I’d say the call centre agent you spoke with was just misinformed, which isn’t unusual for the call centre (but is unusual if you did indeed reach the Hobart centre).
Just make sure it’s reticketed soon enough that you then don’t lose the other flights on the booking.

We’ve had a similar experience, as some OneWorld members (not all) won’t allow ‘infill bookings’. It’s much easier if you need to change one of your return legs, but if it’s an outbound or intermediate leg you’re probably going to need to do it or leave it.

Like you, we also left it!

If you’re talking to people in Hobart, you’re almost certainly talking to the most knowledgeable people in the system, so I don’t know where you can get a more educated opinion.