add-to-functions.php

<?php
//don't add the opening php

// goes inside functions.php file in a child GENESIS CHILD THEME ONLY
/*====== PAGE CHILDREN ===================================================================================================================================================
/* If the page has sub pages, those pages and the title of the parent page shows up as a menu in the sidebar (if there's a sidebar)
/* if the page is set to full width, then nope
/* @genesis_sidebar
/* ul child is .children
/* reference in part List topmost ancestor and its immediate children title on this page:
   https://codex.wordpress.org/Function_Reference/wp_list_pages#List_subpages_even_if_on_a_subpage
/* @since 1.0.0
=========================================================================================================================================================================== */
add_action( 'genesis_sidebar', 'cab_child_pages', 5 );
function cab_child_pages() {
if (is_page()) {
 global $post; 
  if(!function_exists('get_post_top_ancestor_id')){
     function get_post_top_ancestor_id(){
       global $post;
       if($post->post_parent){
          $ancestors = array_reverse(get_post_ancestors($post->ID));
          return $ancestors[0];
      }
      return $post->ID;
    }
} // end if the function does not exist create one
// check if the the page has children
if($post->post_parent)
$children = wp_list_pages("title_li=&child_of=".$post->post_parent."&echo=0"); 
 else
$children = wp_list_pages("title_li=&child_of=".$post->ID."&echo=0");
//show on pages with children
      if ($children) {
        echo '<div class="widget widget_nav_menu"><ul>';
        wp_list_pages( array('title_li'=>'','include'=>get_post_top_ancestor_id()) );
        wp_list_pages( array('title_li'=>'','depth'=>4,'child_of'=>get_post_top_ancestor_id()) );
        echo '</ul></div>';
      }
  
   } //end if is page 
  
} //end cab_child_pages function