old_contents: class BHSRouter(object):
      """A router to control all database operations on models in the bhs application."""
  
      def db_for_read(self, model, **hints):
          """Attempt to read bhs models go to bhs_db."""
          models = [
              'person',
              'group',
              'member',
              'officer',
              'chart',
              'repertory',
          ]
          if model._meta.app_label == 'bhs' and model._meta.model_name in models:
              return 'default'
          elif model._meta.app_label == 'bhs':
              return 'bhs_db'
          return None
  
      def db_for_write(self, model, **hints):
          """Attempt to write bhs models go to bhs_db."""
          models = [
              'person',
              'group',
              'member',
              'officer',
              'chart',
              'repertory',
          ]
          if model._meta.app_label == 'bhs' and model._meta.model_name in models:
              return 'default'
          if model._meta.app_label == 'bhs':
              return 'bhs_db'
          return None
  
      def allow_relation(self, obj1, obj2, **hints):
          """Allow relations if a model in the bhs app is involved."""
          models = [
              'person',
              'group',
              'member',
              'officer',
              'chart',
              'repertory',
          ]
          if (obj1._meta.app_label == 'bhs' and obj1._meta.model_name in models) or (obj2._meta.app_label == 'bhs' and obj1._meta.model_name in models):
              return True
          return None
  
      def allow_migrate(self, db, app_label, model_name=None, **hints):
          """Make sure the bhs app only appears in the 'bhs_db' database."""
          models = [
              'person',
              'group',
              'member',
              'officer',
              'chart',
              'repertory',
          ]
          # if app_label == 'bhs' and model_name in models:
          #     return True
          # if app_label == 'bhs':
          #     return False
          return True
  
new_contents: class BHSRouter(object):
      """A router to control all database operations on models in the bhs application."""
  
      def db_for_read(self, model, **hints):
          """Attempt to read bhs models go to bhs_db, otherwise to default."""
          models = [
              'bhs.human',
              'bhs.structure',
              'bhs.status',
              'bhs.membership',
              'bhs.subscription',
              'bhs.role',
              'bhs.join',
          ]
          if model._meta.label_lower in models:
              return 'bhs_db'
          return None
  
      def db_for_write(self, model, **hints):
          """Attempt to write bhs models go to bhs_db, otherwise to default."""
          models = [
              'bhs.human',
              'bhs.structure',
              'bhs.status',
              'bhs.membership',
              'bhs.subscription',
              'bhs.role',
              'bhs.join',
          ]
          if model._meta.label_lower in models:
              return 'bhs_db'
          return None
  
      def allow_relation(self, obj1, obj2, **hints):
          """Reject relations if a model in the bhs app is involved."""
          models = [
              'bhs.human',
              'bhs.structure',
              'bhs.status',
              'bhs.membership',
              'bhs.subscription',
              'bhs.role',
              'bhs.join',
          ]
          if (obj1._meta.label_lower in models) and (obj2._meta.label_lower not in models):
              return False
          return None
  
      def allow_migrate(self, db, app_label, model_name=None, **hints):
          """Make sure the bhs app only appears in the 'bhs_db' database."""
          models = [
              'human',
              'structure',
              'status',
              'membership',
              'subscription',
              'role',
              'join',
          ]
          if app_label == 'bhs' and model_name in models:
              return False
          return None
  
subject: Update routers.py