code: def formfield_for_manytomany(self, db_field, request, **kwargs):
          
          if db_field.name == 'authors':
              kwargs['queryset'] = Author.objects.filter(
                  Q(is_staff=True) | Q(entries__isnull=False)
                  ).distinct()
  
          return super(EntryAdmin, self).formfield_for_manytomany(
              db_field, request, **kwargs)
docs: Filter the disposable authors.