title: Get siblings from custom post type
body: <p>I have setup an custom post type with the structure below:</p>
  
  <ul>
  <li>Main post
  
  <ul>
  <li>Children post
  
  <ul>
  <li>Sibling post</li>
  </ul></li>
  </ul></li>
  </ul>
  
  <p>I have two main posts called "Vrouwen" en "Mannen"
  When i visit one of these main posts i would like to only display the siblings.</p>
  
  <p>Im stuck in achieving this.</p>
  
  <p>But then the "children" are also displayed.
  I need to go one level deeper somehow.</p>
  
  <p>All help is appreciated!</p>
  
  <p>I tried the code below.</p>
  
  <pre><code>$mysibling        = $post-&gt;post_parent;
  $mychild          = $post-&gt;ID;
  $mychildmysibling = array( $mychild, $mysibling );
  
  $args = array(
      'post_parent'    =&gt; $mychildmysibling,
      'post__not_in' =&gt; array( $post-&gt;ID ),
      'posts_per_page' =&gt; -1,
      'post_type'       =&gt; 'collectie'
  );
  
  $parent = new WP_Query( $args );
  while ( $parent-&gt;have_posts() ) : $parent-&gt;the_post();
  </code></pre>
  
  <p>But then the "children" are also displayed. I need to go one level deeper somehow.</p>