Ideally I'd set up categories with group permissions as follows:
Team Communication
Permission: Team1, Team2, Team3
- A main category for communication among members of a number of teams who contribute to a common goal.
Team1 Comms
Permission: Team1
- A subcategory for Team1 communication in their specific area of responsibility.
Team2 Comms
Permission: Team2
etc
Currently subcategories are forced to inherit the permissions of the main category.
It would make sense, at lease in my use case, to force permissions in the other direction.
i.e. to force the permissions for categories Team1 Comms, Team2 Comms etc on Team Communication