public function maintain_gallery_during_attach_and_detach( $action, $attachment_id, $parent_id ) {
		$parent_id = intval( $parent_id );
		if ( 'detach' === $action ) {
			$this->remove_attachment_from_gallery( $attachment_id, $parent_id );
			// Is this photo set as the Featured Image?
			if ( (int) get_post_meta( $parent_id, '_thumbnail_id', true ) === $attachment_id ) {
				// Yes. Remove it.
				delete_post_thumbnail( $parent_id );
			}
			// Remove vehicle-specific meta values.
			delete_post_meta( $attachment_id, apply_filters( 'invp_prefix_meta_key', 'photo_number' ) );
			delete_post_meta( $attachment_id, apply_filters( 'invp_prefix_meta_key', 'vin' ) );
			Inventory_Presser_Photo_Numberer::renumber_photos( $parent_id );
			return;
		}
		$this->add_attachment_to_gallery( $attachment_id, $parent_id );
	}