Conquered all Hungarian Core Territory
Death or Dishonor will give Hungary new cores while Together for Victory will make Australia a dominion under the United Kingdom when changing ideologies rather than an independent faction member so it may be best to turn off these DLC.
To reach Hungary and have it in Australian control, it is required to build paratroopers, transport planes and interwar fighters. For the focus tree, take the Political Effort focus in the generic focus tree. Take the Fascist Demagogue and take the Political discourse decisions. Take decisions that speed up fascism growth like the Discredit government and expand civil support if necessary. As soon as Australia turns Fascist, leave the Allies and join the Axis. Justify against Hungary. Send the troops to Southern Germany. Wait for Anschluss. After Anschluss, set one paratrooper to each of the victory points from Austria. then put some on the west of the leftmost river in Hungary. Most of the Hungarian troops are on the German border. Place your extra troops there just in case. When ready, declare on Hungary and send the paratroopers. It is not necessary to have the Germans help. If done correctly, the last paratrooper will be enough to capitulate Hungary.