Hi Bound4Tassie,
As i got your point, you shouldn't certify this your yourself, I got this reply from Australian immigration website
"Any person or agency recognised by the law of the country in which you live can certify documents. All our offices outside Australia have a person who can certify or witness documents. You might have to pay for this service."
So, I prefer you to choose either Australian embassy, Australian Lawyer, Australian Migration agent, Australian Barriester, Australin Soliciter, Australian Pharmacist.. to certify these documents for you.
Thank you.