Speak to a lawyer immediately. Your options will depend on an evaluation of all the circumstances.
If you have parenting order that children live with you, or the children normally live with you, and the other party has taken or is withholding them without agreement, you can apply to the Court for a recovery order. If the children are at immediate risk, the Court will hear your matter without delay.
A recovery order allows State and Federal police to locate the children. They will have wide entry and enforcement powers to do this. If the children have a passport, ask the Court for an Airport Watchlist Order. This will prevent the children from leaving Australia.
If the children are not at immediate risk, and you don’t know where they are, you can ask the Court for a location order which allows government departments to examine their databases and provide information to the Court registry.
If the children have not been returned from overseas, speak to a lawyer immediately. Australia has an agreement with many other countries about the return of children removed without agreement. The Australian government will, with the help of your lawyer, apply to have the children returned to Australia.
Before agreeing to the children travelling overseas, check the list of countries that have signed to Hague Convention on the Commonwealth Attorney-General website.
If the proposed country is not listed, the Australian government will have no power to seek the return of your children.