code: public function updateCMSFields(FieldList $fields) {
  
  		$fields->removeByName('FusionTags');
  
  		// Determine whether consolidated tags are found in the existing relationships.
  
  		$types = array();
  		foreach(singleton('FusionService')->getFusionTagTypes() as $type => $field) {
  			$types[$type] = $type;
  		}
  		$types = array_intersect($this->owner->many_many(), $types);
  		if(empty($types)) {
  
  			// There are no consolidated tags found, therefore instantiate a tagging field.
  
  			$fields->addFieldToTab('Root.Tagging', ListboxField::create(
  				'FusionTags',
  				'Tags',
  				FusionTag::get()->map()->toArray()
  			)->setMultiple(true));
  		}
  
  		// Allow extension.
  
  		$this->owner->extend('updateTaggingExtensionCMSFields', $fields);
  	}
docs: Display the appropriate tagging field.