Always show 2 specifics tags

Kirby 2 Questions 🤔
1

Hello,

I’m trying to deal with tags to categorize some content (I maybe should have done things diferently before…)
I’ve a page with subpages. All subpages have some tags witch are displayed in an aside nav.
There are 2 of these tags I would need to show (correctly) in all subpages. Here is an exemple :

<?php if($page->parents()->find('collections')): ?>
    <nav class="nav">
    <h3>Tags:</h3>
    <ul>
       <?php foreach(str::split($page->tags()) as $tag): ?>
        <li>
           <a  href="<?php echo url('collections/' . url::paramsToString(['cat' => $tag])) ?>">#<?php echo $tag; ?></a>
        </li>
    <?php endforeach ?>
   </ul>
   </nav>

   <nav class="nav">
   <h3>Catégorie:</h3>
   <ul>        
      <li>
        <a  href="<?php echo url('collections/cat;tag1') ?>">#tag1</a>
      </li>
      <li>
        <a  href="<?php echo url('collections/cat;tag2') ?>">#tag2</a>
      </li>       
</ul>
</nav>
<?php endif; ?>

Thank you for your help,