The ACT, as a small and compact city, should not simply follow the model of other state jurisdictions in administration. ACT government and the Legislation Assembly should think creatively and consider the most efficient and effective administration style and model to suit such a small city state/territory.
I would argue that one way is for the ACT to have a default or fallback position to use laws and policies in the NSW, and only to have a different one if there is a two third majority in both the assembly and the general ACT population. After all, the ACT is within NSW and a part of Australia and one would not expect there are so many different situations between it and NSW, apart from the ACT virtually does not have rural, agriculture, mining and is much simpler to administrate.
This means there would only be a need for front line services as opposed to duplication of unnecessarily so many central administrative agencies/politicians/bureaucrats staff for policy and central administration. The ACT government should effectively, largely and essentially be a city administration like a small council.
The two main sides of politics and the Greens should have the welfare of the ACT residents in mind and should endeavor to be more efficient in administration of the ACT affairs. It is not too dissimilar to the differences in business administration and management between large and small businesses.
In that context, the idea of further expansion reflects very poorly on the creativity of those proponents of such an bad idea.