If you have a court order you can file an application with the child support agency in Australia and they will collect for you.
Even without a court order they will assess him and then collect it for you
The following link is for the agency.
You can use the links to work out what he has to pay and also apply directly online.
They will collect and send the money to you overseas.
I hope this has assisted you with your question today.
If you wish to have a phone call to discuss this in more detail please elect a call or I can send you a request.
I hope this makes sense and is of assistance. If you have found my answer to be helpful, please rate me five stars so I can get paid for my services to you. You rating my work 5 stars allows me to continue to provide a service to those who require it.
I am happy for you to ask further questions on anything you wish more detail on.
Let me know if I have answered your question today.