part codes

// add region category to main queries
add_action('pre_get_posts', 'tg_set_region');
function tg_set_region( $query ) {
    //--------debug-----------
//if ( !is_admin() && $query->is_main_query())
 //  print_r( $query );
//-----------------------
  if ( get_option('page_on_front') == $query->get('page_id')) return;
  if ( !is_admin() && $query->is_main_query()) {
    global $region;
    $explode = explode('/', $_SERVER['REQUEST_URI']);
    $cat = $query->get('category_name');
    $region = $explode[1];  // $region = 'benelux'; //$explode[1];
    if ( '' != $cat ) $cat .= '+' . $region;
        else $cat = $region;
    $query->set('category_name', $cat);
  }
}


and



// Insert region into post links
add_filter('post_link', 'tg_add_region', 999, 3 );
function tg_add_region( $link, $post, $leavename) {
   global $region;
   $link = str_replace('.com/', ".com/$region/", $link );
   return $link;
}