Hi Adele,
If Council doesn’t have an aggregation policy, you can only assess the application by following Section 548A (1).
When I was at North Sydney, the policy was for a maximum of one residential or business unit to be aggregated with one car space and one storage cage/room. Note that when you assess the application, it must qualify using both tests in s548A (1) (a) & (b). How you assess is a matter for Council but when discussing with your Finance Manager, if a developer is prepared to pay for multiple lots in the plan it’s hard to believe that separate rate assessments would cause them any hardship. There are some good discussions on this matter in the historic documents as well.
Hope this helps.