我没有完全测试下面描述的方法，也没有测试正常的“孙子”主题，但给出了template_include 过滤器：

    /*
    Plugin Name: Grandchild Themes
    Plugin URI: http://www.who-cares.com/
    Description: A concept for Grandchild themes Plugin
    Author: See Plugin URI
    Version: 0.0.0.0.1-Alpha
    */

    add_action(\'wp_head\', \'grnd_chld_add_headers\', 0);
    add_action(\'init\', \'grnd_chld_add_css\');

    // Load template if exists. 
function grandchild_template_include( $template ) {

    if ( file_exists( untrailingslashit( plugin_dir_path( __FILE__ ) ) . \'/grnd_chld_templates/\' . basename( $template ) ) )
        $template = untrailingslashit( plugin_dir_path( __FILE__ ) ) . \'/grnd_chld_templates/\' . basename( $template );

    return $template;
}

// This is the actual filter that we want .
add_filter( \'template_include\', \'grandchild_template_include\', 11 );

    function grnd_chld_add_headers () {
        wp_enqueue_style(\'my_grandchild_style\');
    }

    function grnd_chld_add_css() {
        $stamp = @filemtime(plugin_dir_path(__FILE__).\'/style.css\'); // easy versioning
        wp_register_style (\'my_grandchild_style\', plugins_url(\'style.css\', __FILE__).\'\', array(), $stamp);
    }

    // From here , what you got is like a normal functions.php.

add_filter (\'archive_template\', create_function (\'\', \'return plugin_dir_path(__FILE__)."archive.php";\'));