Pull Child Page Content into Parent Page - WordPress

ChildPagetoParent_WordPress.php

<div class="entry-content">
    <?php the_content(); ?>

    <?php
        $childArgs = array(
            'sort_order' => 'ASC',
            'sort_column' => 'menu_order',
            'child_of' => get_the_ID()
        );
        $childList = get_pages($childArgs);
        foreach ($childList as $child) { ?>
            <div class="child-page">
                <h2 class="child-title"><?php echo $child->post_title; ?></h2>
                <?php echo apply_filters( 'the_content', $child->post_content); ?>
            </div>
        <?php } ?>

    <?php
        $pagelist = get_pages('sort_column=menu_order&sort_order=asc&parent=0');
        $pages = array();
        foreach ($pagelist as $page) {
            $pages[] += $page->ID;
        }

        $current = array_search(get_the_ID(), $pages);
        $prevID = $pages[$current-1];
        $nextID = $pages[$current+1];
    ?>

    <ul class="page-nav">
        <?php if (!empty($prevID)) { ?>
            <li class="previous">
                <a href="<?php echo get_permalink($prevID); ?>" title="<?php echo get_the_title($prevID); ?>"><span aria-hidden="true">&larr;</span> <?php echo get_the_title($prevID); ?></a>
            </li>
        <?php }
        if (!empty($nextID)) { ?>
            <li class="next">
                <a href="<?php echo get_permalink($nextID); ?>" title="<?php echo get_the_title($nextID); ?>"><?php echo get_the_title($nextID); ?> <span aria-hidden="true">&rarr;</span></a>
            </li>
        <?php } ?>
    </ul><!-- .navigation -->
</div>