When I renew my medicare card, I need to go to Medicare service office.
They want me to proof that I am going to live permanently in Australia.
They asked me for 3 proof:
1. shipping documents - confirming goods are shipping back to Australia
2. Proof of selling house overseas / buying home in australia
3. Opening of bank account.
Adding your child is easy. Once you have renew yours, just bring the child's birth certificate.