经过大量的尝试和测试，我想我找到了一个解决方案：

add_filter( \'sidebars_widgets\', \'exchange_sidebars\', 10);

function exchange_sidebars( $sidebars_widgets ){
    global $post;
    // Define the sidebar which should be exchanged
    $selected_sidebar = \'sidebar-1\'

    // IF we are on a custom post type
    // AND it is a Child Page (= page has post_parent)
    // THEN change selected sidebare with courses-lessons sidebar
    if ( is_singular(\'courses\') && $post->post_parent && $sidebars_widgets[\'courses-lessons-sidebar\'] ) {
        $sidebars_widgets[$selected_sidebar] = $sidebars_widgets[\'courses-lessons-sidebar\'];

    // IF we are on a custom post type
    // AND it is a Parent Page (= page has no post_parent)
    // THEN change selected sidebare with courses-overview sidebar
    }elseif( is_singular(\'courses\') && !$post->post_parent && $sidebars_widgets[\'courses-overview-sidebar\'] ) {
        $sidebars_widgets[$selected_sidebar] = $sidebars_widgets[\'courses-overview-sidebar\'];
    }
    return $sidebars_widgets;
}