В breadcrumbs вывести все дочерные рубрики

function zt_the_breadcrumb() { ?>
<div class="page-callout">
<div class="container">
<div class="row">
<div class="span6">
<?php zt_the_breadcrumb_data(); ?>
</div>
 
<div class="span6">
<div class="page-name">
<?php the_title(); ?>
</div>
</div>
</div>
</div>
</div>
 
<?php 
}
 
function zt_the_breadcrumb_data() {
echo '<div class="breadcrumbs">'. __('You are here', 'avian') .':<ul>';
if (!is_home()) {
echo '<li><a href="';
echo home_url();
echo '">';
echo '<i class="fa fa-home"></i> ' . __('Home', 'avian');
echo "</a></li>";
if (is_category() || is_single()) {
echo '<li>';
the_category(' </li><li> ');
echo '</li>';
 
 
if (is_category()) {
echo '</div>';
}
if (is_single()) {
echo "</li><li>";
the_title();
echo '</li>';
echo '</div>';
}
} elseif (is_page()) {
global $post; 
$parent_title = get_the_title($post->post_parent); 
if ($post->post_parent) {
echo '<a href="'.get_permalink($post->post_parent).'">'.$parent_title.'</a>';
}
echo '<li>';
echo the_title();
echo '</li>';
echo '</div>';
} else {
echo '</div>';
}
}
elseif (is_tag()) {single_tag_title();}
elseif (is_day()) {echo"<li>Archive for "; the_time('F jS, Y'); echo'</li>';}
elseif (is_month()) {echo"<li>Archive for "; the_time('F, Y'); echo'</li>';}
elseif (is_year()) {echo"<li>Archive for "; the_time('Y'); echo'</li>';}
elseif (is_author()) {echo"<li>Author Archive"; echo'</li>';}
elseif (isset($_GET['paged']) && !empty($_GET['paged'])) {echo "<li>Blog Archives"; echo'</li>';}
elseif (is_search()) {echo"<li>Search Results"; echo'</li>';}
elseif (is_home()) { echo '</div>'; }
echo '</ul>';
 
}
 
function menu_set_dropdown( $sorted_menu_items, $args ) {
$last_top = 0;
foreach ( $sorted_menu_items as $key => $obj ) {
// it is a top lv item?
if ( 0 == $obj->menu_item_parent ) {
// set the key of the parent
$last_top = $key;
} else {
$sorted_menu_items[$last_top]->classes['dropdown'] = 'dropdown';
}
}
return $sorted_menu_items;
}
add_filter( 'wp_nav_menu_objects', 'menu_set_dropdown', 10, 2 );

$thiscat =  get_query_var('cat'); // The id of the current category
$catobject = get_category($thiscat,false); // Get the Category object by the id of current category
$parentcat = $catobject->category_parent; // the id of the parent category

get_categories( array( 'child_of' => $parentcat ) ); // см документацию