How many categories can discourse support?

I’m also looking into securing conversations between a patient and a medic.
The only solution I found so far by reading the documentation is to:

  • create a category for the user via API
  • create a group for the user via API
  • assign the pationt group, the medic and the staff groups to the category

This way, the patient can and the medic can have interactions that only they can see.
Also more medics could be added to the discussion and they would see the discussions.
Staff can oversee for abuse.