WordPress custom taxonomy parent-child navigation menu -

i'm trying create following menu structure custom taxonomies:

cat 1 -subcat1 -subcat2  cat 2 cat 3 cat 4 

what want achieve when click on child category (subcat1 example) current navigation structure should stay same, , bold current subcat. when click on parent category, it's subcategories should appear , the rest of parent cats (not cats subcats).

my problems following:

i managed create child navigation menu when clicking on parent category, shows current , child level categories in menu, without other main categories using code:

<?php $taxonomy     = $tax; $orderby      = 'name';  $show_count   = 1;      // 1 yes, 0 no $pad_counts   = 0;      // 1 yes, 0 no $hierarchical = 1;      // 1 yes, 0 no $title        = ''; if (get_term_children($term->term_id, $tax) != null) { $child = $term->term_id; } else { $child = ''; } $args = array(   'taxonomy'     => $taxonomy,   'orderby'      => $orderby,   'show_count'   => $show_count,   'pad_counts'   => $pad_counts,   'hierarchical' => $hierarchical,   'title_li'     => $title,   'child_of'     => $child,   'current_category'   => 0  ); ?> <? if (get_term_children($term->term_id, $tax) != null) { ?> <h3><?php echo $term->name; ?> templates</h3> <? } ?> <?php  wp_list_categories( $args ); ?> 

the problem above code when click on child category parent/subcategories displayed again.

i want able stay on same structure when browsing of subcategories 1 big category addition of bold font face subcategory i'm browsing.

if makes sense please help.

thanks,

what create custom query loop through taxonomy parent of 0 in loop of displaying them get_term_children function. believe best way create this. have done in plugin , has allowed me have more customisation.