Inpsyde\MultilingualPress\API\ContentRelations::has_site_relations PHP Method

    public function has_site_relations($site_id, $type = '');

 /**
  * Sets up content relations between the source site and the new site.
  *
  * @param int $source_site_id      The ID of the source site.
  * @param int $destination_site_id The ID of the new site.
  *
  * @return void
  */
 private function handle_content_relations($source_site_id, $destination_site_id)
 {
     if ($this->content_relations->has_site_relations($source_site_id)) {
         $this->content_relations->duplicate_relations($source_site_id, $destination_site_id);
         return;
     }
     $this->content_relations->relate_all_posts($source_site_id, $destination_site_id);
     $this->content_relations->relate_all_terms($source_site_id, $destination_site_id);
 }