I kinda solved the problem myself. It's not the most elegant way but works fine for me...
In includes/templates/westminster_new/common/tpl_footer.php I replaced
<!--bof-flexible footer menu display -->
<div id="flex-navSupp">
<div class="onerow-fluid <?php echo $fluidisFixed; ?>">
<?php require($template->get_template_dir('tpl_flexible_footer_menu.php',DIR_WS_TEMPLATE, $current_page_base,'templates'). '/tpl_flexible_footer_menu.php'); ?>
<br /><br />
with
<!--bof-own footer menu display -->
<div id="flex-navSupp">
<div class="onerow-fluid ">
<div class="flexFooterCol ffCcol1" style="width: 32.4%"><ul><li><h4><?php echo FLEXI_SHOP; ?></h4></li>
<li><a href="index.php?main_page="><?php echo FLEXI_HOME; ?></a></li>
<li><a href="index.php?main_page=featured_products"><?php echo FLEXI_FEATURED; ?></a></li>
<li><a href="index.php?main_page=specials"><?php echo FLEXI_SPECIALS; ?></a></li>
<li><a href="index.php?main_page=products_new"><?php echo FLEXI_NEWARRIVALS; ?></a></li>
<li><a href="index.php?main_page=products_all"><?php echo FLEXI_VIEWALL; ?></a></li>
</ul></div><div class="flexFooterCol ffCcol2" style="width: 32.4%"><ul><li><h4><?php echo FLEXI_CUSTOMERSERVICE; ?></h4></li>
<li><a href="index.php?main_page=shippinginfo"><?php echo FLEXI_SHIPPINGANDRETURNS; ?></a></li>
<li><a href="index.php?main_page=contact_us"><?php echo FLEXI_CONTACTUS; ?></a></li>
<li><a href="index.php?main_page=about_us" class="activePage"><?php echo FLEXI_ABOUTUS; ?></a></li>
<li><a href="index.php?main_page=account"><?php echo FLEXI_MYACCOUNT; ?></a></li>
</ul></div><div class="flexFooterCol ffCcol4" style="width: 32.4%"><ul><li><h4><?php echo FLEXI_SHAREANDCONNECT; ?></h4></li>
<li class="flexFooterColText"><a href="https://www.facebook.com/Custom.Zen.Cart.Design" target="_blank"><i class="fa fa-facebook"></i></a><a href="https://twitter.com/picaflorazul" target="_blank"><i class="fa fa-twitter"></i></a><a href="http://www.pinterest.com/picaflorazul" target="_blank"><i class="fa fa-pinterest"></i></a><a href="https://www.youtube.com/user/ZenCartEasyHelp" target="_blank"><i class="fa fa-youtube"></i></a><a href="" target="_blank"><i class="fa fa-instagram"></i></a></li>
</ul></div><br class="clearBoth" /><br /><br />
<!--eof-own footer menu display -->
<!--bof-flexible footer menu display -->
<!--<div id="flex-navSupp">
<div class="onerow-fluid <?php echo $fluidisFixed; ?>">
<?php require($template->get_template_dir('tpl_flexible_footer_menu.php',DIR_WS_TEMPLATE, $current_page_base,'templates'). '/tpl_flexible_footer_menu.php'); ?>
<br /><br />-->
After that I had to make the defines in the language files...
I added to includes/languages/westminster_new/english.php
// defines Own Flexi Menu
define('FLEXI_SHOP', 'Shop');
define('FLEXI_HOME', 'Home');
define('FLEXI_FEATURED', 'Featured Items');
define('FLEXI_SPECIALS', 'Specials');
define('FLEXI_NEWARRIVALS', 'New Arrivals');
define('FLEXI_VIEWALL', 'View all');
define('FLEXI_CUSTOMERSERVICE', 'Customer Service');
define('FLEXI_SHIPPINGANDRETURNS', 'Shipping and Returns');
define('FLEXI_CONTACTUS', 'Imprint & Contact');
define('FLEXI_ABOUTUS', 'About Us');
define('FLEXI_MYACCOUNT', 'My Account');
define('FLEXI_SHAREANDCONNECT', 'Share and Connect');
And toincludes/languages/westminster_new/german.php
// defines Own Flexi Menu
define('FLEXI_SHOP', 'Shop');
define('FLEXI_HOME', 'Homepage');
define('FLEXI_FEATURED', 'Empfohlene Artikel');
define('FLEXI_SPECIALS', 'Sonderangebote');
define('FLEXI_NEWARRIVALS', 'Neue Artikel');
define('FLEXI_VIEWALL', 'Alle Artikel');
define('FLEXI_CUSTOMERSERVICE', 'Kundenservice');
define('FLEXI_SHIPPINGANDRETURNS', 'Lieferung und Versand');
define('FLEXI_CONTACTUS', 'Impressum & Kontakt');
define('FLEXI_ABOUTUS', 'Über uns');
define('FLEXI_MYACCOUNT', 'Kundenkonto');
define('FLEXI_SHAREANDCONNECT', 'Weitersagen');
