My WordPress blog is set up as `nl_NL`. This means that my [bookly plugin](http://booking-wp-plugin.com/) is also displayed in `nl_NL`.

In the Plugin directory there is a folder languages with loads of other languages.

I have one page in three different languages `nl_NL`, `de_DE`, `en_EN`, on this page I would like the booking plugin to be displayed in the correct language. 

I changed the page language via page id from `nl_NL` to `de_DE`

Via the `function.php`, but this had no effect. 

```
function get_top_parent_page_id() { 
    global $post; 

    if ($post->ancestors) { 
        return end($post->ancestors); 
    } else { 
        return $post->ID; 
    } 
}

function addLangMetaTag (){
    $postLanguage = "nl_NL";
    if (is_page()) {
    $svPageID = get_top_parent_page_id(); // ID of parent page
            if ($svPageID == "13040") { // ID of the "på svenska" page
                $postLanguage = "de_DE";    
            }
        echo "<meta http-equiv=\"content-language\" content=\"" . $postLanguage . "\">";
    }
}
add_filter( 'wp_head', 'addLangMetaTag' );

function language_tagger_change_html_lang_tag() {
    return "dir=\"ltr\" lang=\"" . 
language_tagger_determin_lang_tag() . "\"";
}

function language_tagger_determin_lang_tag() {
    $postLanguage = 'nl_NL'; // default language
    if (is_page()) {
    $svPageID = get_top_parent_page_id(); // ID of parent page
    if ($svPageID == "13040") { // ID of the "på svenska" page
                $postLanguage = "de_DE";    
            }
    }
    return $postLanguage;
}

add_filter('language_attributes', 
'language_tagger_change_html_lang_tag');

```

I think it will only look at the WordPress `config.php` `define('WPLANG', 'nl_NL');`
I have also been reading [this post](https://wordpress.stackexchange.com/questions/72692/how-do-i-change-the-language-of-only-the-login-page#) maybe I could combine something?