Creates 'fake' sub-pages for custom post types in WordPress. In this example we are creating 3 sub-pages called "About", "People" and "Information" for the CPT "department"

create-sub-pages-for-custom-post-type.php

<?php
/*
*  Creates fake sub pages for a custom post type.
*/

// Create 'Fake sub-pages' permalinks and titles.
$sub_pages = array(
	'about' => 'About',
	'people' => 'People',
	'information' => 'Information',
);

add_filter('rewrite_rules_array', 'ace_insertrules');
add_filter('query_vars', 'ace_insertqv');

// Adding fake sub-pages' rewrite rules
function ace_insertrules($rules)
{
	global $sub_pages;

	$newrules = array();
	foreach ($sub_pages as $slug => $title)
		$newrules['department/([^/]+)/' . $slug . '/?$'] = 'index.php?department=$matches[1]&fpage=' . $slug; // department is the name of our custom post type

	return $newrules + $rules;
}

// Tell WordPress to accept our custom query variable
function ace_insertqv($vars)
{
	array_push($vars, 'fpage');
	return $vars;
}

// Remove WordPress's default canonical handling function
remove_filter('wp_head', 'rel_canonical');
add_filter('wp_head', 'ace_rel_canonical');

function ace_rel_canonical() {
		global $current_sp, $wp_the_query;

		if (!is_singular())
			return;

		if (!$id = $wp_the_query->get_queried_object_id())
			return;

		$link = trailingslashit(get_permalink($id));

		// Make sure sub-pages' permalinks are canonical
		if (!empty($current_sp))
			$link .= user_trailingslashit($current_sp);

		echo '<link rel="canonical" href="'. $link .'" />';
	}

// If using Yoast - remove the canonical link from your custom post type as we set proper canonical tags above.
function ace_seo_canonical_exclude( $canonical ) {
	global $post;
	if (is_singular('department')) {
		$canonical = false;
	}
	return $canonical;
}

add_filter( 'wpseo_canonical', 'ace_seo_canonical_exclude' );

single-department.php

<?php

/**
 * Department single page template
 * We have created sub (fake) pages in create-sub-pages-for-custom-post-type.php to display content from our custom posts types that have a relationship with the current Department
 * This is so we can have the correct permalink 
 */


// get the current sub-page slug
$current_sp = get_query_var('fpage');

// If we have a sub-page slug and are therefore on a sub-page then remove the standard loop so we don't show the content of the parent post on sub-pages
if ($current_sp) {
        remove_action( 'genesis_loop', 'genesis_do_loop' );
        add_action ('genesis_loop', 'ace_get_subpage_template');
}

// Get the current sub-page slug and load the correct template part
function ace_get_subpage_template() {

    $current_sp = get_query_var('fpage');

     if ( $current_sp == 'about' ) {
            get_template_part('template-parts/self-advocacy-groups/about');

        }
        else if ( $current_sp == 'information' ) {
            get_template_part('template-parts/self-advocacy-groups/information');

        }
        else if ( $current_sp == 'people' ) {
            get_template_part('template-parts/self-advocacy-groups/people');

        }
}

genesis();