With wp_list_pages I use a code like this underneath. Can something similair been made with wp_nav_menu()?
<?php
$parent_title = get_the_title($post->post_parent);
$output = wp_list_pages('echo=0&depth=1&title_li=Top Level Pages&exclude=13,2' );
if (is_page( )) {
$page = $post->ID;
if ($post->post_parent) {
$page = $post->post_parent;
}
$children=wp_list_pages( 'echo=0&child_of=' . $page . '&title_li=' );
if ($children) {
$output = wp_list_pages ('echo=0&child_of=' . $page . '&title_li='.$parent_title.' ');
}
}
echo $output;
}
?>