So every book (US, Germany, Japan, etc.) has a clearly labeled and outlined Generic Reinforced Platoon, along with national special rules.
The Australians in the New Guinea book do not. They have special rules which replace the British ones, unique units, and theatre selectors. But they do not have a GRP, as far as I can see.
Do they just use a British GRP and swap special rules, loosing access to their special units in a GRP? The summary of their national rules sees to strongly imply this.