In my first foray into scenario modding, I simply replaced the I Corps supply base with the 6 Aus. Div supply base (Mackay force's organic supply base according to the OOB). Simple drag-and-drop replacement, and the allied supply works out much better.
While delving around with the OOB's in the scenario editor, I was looking at the OOB for the I Aus Corps. It appears in the OOB to have only a single subordinate formation, Mackay Force, other than the base. Like so:
