/* 加载页面模板 */
add_filter( 'page_template', 'marker_page_template' );
function marker_page_template( $page_template ) {
    if ( get_page_template_slug() == 'markerv' ) {
        $page_template = MARKER_DIR . '/templates/markerv.php';
    }
    if ( get_page_template_slug() == 'test' ) {
        $page_template = MARKER_DIR . '/templates/test.php';
    }
    return $page_template;
}

/* 添加到页面属性模板中 */
add_filter( 'theme_page_templates', 'marker_add_template_select', 10, 4 );
function marker_add_template_select( $post_templates, $wp_theme, $post, $post_type ) {
    $post_templates['markerv'] = __( 'markerv' );
    $post_templates['test'] = __( 'test' );
    return $post_templates;
}

模板文件：markerv.php

模板文件路径：/templates/markerv.php

显示在页面属性中的模板名称：$post_templates[‘markerv’] = __( ‘模板名称’);