Taxonomy Term Template Children Inheritance - Children terms inherit the parent taxonomy template.

functions.php

/**
 * Filter the taxonomy hierarchy to inject a parent level of templates.
 * 
 * @param string $template The current template.
 * @return string Filtered taxonomy template.
 */
function new_tax_hierarchy( $template ) {
    $term = get_queried_object();
 
    // If not an object, or the object doesn't have a taxonomy, bail.
    if ( ! is_object( $term ) || ! isset( $term->taxonomy ) )
        return $template;
 
    $taxonomy = $term->taxonomy;
 
    // If the taxonomy isn't hierarchical, bail.
    if ( ! is_taxonomy_hierarchical( $taxonomy ) )
        return $template;
 
    $templates = array();
    $parent_id = $term->parent;
 
    if ( 0 == $parent_id ) {
        // Use default values from get_taxonomy_template().
        $templates[] = "taxonomy-$taxonomy-{$term->slug}.php";
        $templates[] = "taxonomy-$taxonomy.php";
        $templates[] = 'taxonomy.php';
    } else {
        $parent = get_term( $parent_id, $taxonomy );
 
        // Current templates.
        $templates[] = "taxonomy-$taxonomy-{$term->slug}.php";
        $templates[] = "taxonomy-$taxonomy.php";
 
        // Parent templates.
        $templates[] = "taxonomy-$taxonomy-{$parent->slug}.php";
        $templates[] = "taxonomy-$taxonomy-{$parent->term_id}.php";
        $templates[] = 'taxonomy.php';
    }
    return locate_template( $templates );
}
add_filter( 'taxonomy_template', 'new_tax_hierarchy' );

is this code tested? I am trying it with no results!