Once you move just update your address in India. I moved back to India from US after crossing 6 months too and have sent a webform for updating my address. I don't think it will affect the processing of the application much since they will process the application in the current VO and then send the updates to the local VO i.e. New Delhi for us.
I have also heard instances where even though the applicants updated their addresses, the PPR mail requested them to send the passports to the initial VOs (will be Sydney for you). If that happens, you can mail them and say that you'd provided the address change and they'll change the passport receiving VO to New Delhi.