Display Parent Page Title and Child Page Title and Content

Hello, I’m wondering if someone clever can help with this problem.

I have a custom post type which is hierarchical and has page attributes so I can create sub pages.

I’m trying to display the title only of the parent page followed by the title and the content of it’s child pages. For example:

Parent Page Title
– Child Page Title
– Child Page Content

Parent Page Title
– Child Page Title
– Child Page Content

and so on.

The code below almost gets me there but it’s duplicating the child pages in the first bit as h1 titles. How can I exclude the child pages and prevent them from displaying in the first part of the loop?

Maybe there is an easier way to approach this?

Many thanks

<?php

echo "<ul>";
if ( have_posts() ) {
while ( have_posts() ) {
    the_post();
    echo "<li><h1>".get_the_title()."</h1>";

    $args=array(
            'orderby' => 'menu_order',
            'order' => 'ASC',
             'post_parent' => $post->ID,
                 'post_type' => get_post_type( $post->ID ),
            'posts_per_page' => 10
    );

    $childpages = new WP_Query($args);

    if($childpages->post_count > 0) { /* display the children content  */
        echo "<ul>";
        while ($childpages->have_posts()) {
             $childpages->the_post();
             echo "<li><h2>".get_the_title()."</h2></li>";
             echo "<li><h2>".the_content()."</h2></li>";
        }
        echo "</ul>";
    }
    wp_reset_query();

    echo "</li>";
     }
    }
   echo "</ul>";
 ?>