code: def move_chosen_subscribers(self):
          
          from_channel = Channel.objects.get(self.current.task_data['chosen_channels'][0])
          to_channel = Channel.objects.get(self.current.task_data['target_channel_key'])
  
          with BlockSave(Subscriber, query_dict={'channel_id': to_channel.key}):
              for subscriber in Subscriber.objects.filter(
                      key__in=self.current.task_data['chosen_subscribers']):
                  subscriber.channel = to_channel
                  subscriber.save()
  
          if self.current.task_data['new_channel']:
              self.copy_and_move_messages(from_channel, to_channel)
  
          self.current.task_data[
              'msg'] = _(u"Chosen subscribers and messages of them migrated from '%s' channel to "
                         u"'%s' channel successfully.") % (from_channel.name, to_channel.name)
docs: After splitting operation, only chosen subscribers
          are moved to new channel or existing channel.