I think Anzac should take a clear mission for itself. My last game I assigned to Anzac the occupation and defence of the DEI money islands. These are worth 16 IPC to the allies and even 20 IPC to Japan. I just occupy these islands with just enough infantry to make it difficult for Japan to take them without making a sizeable investment.
Even if Japan makes this investment you have succeeded: Japan is not investing that IPC in China/India!
If JP leaves the islands alone, Anzac can build a fleet to support the US!