Check if Page has Siblings

April 17, 2019

Works great if you’re using a sub-menu that shows related-level items when on a page.

function has_sibling() {
     global $post;
     if ( $post->post_parent ) {
          $siblings = get_pages( 'child_of='.$post->post_parent );
          if ( count($siblings) > 1 ) {
               return true;
          } else {
               return false;
          }
     } else {
          return false;
     }
}

Source.