Drupal 7: Dynamic term generation for exsisting parent

example

$vocab_machine_name = 'name';
$vacab = taxonomy_vocabulary_machine_name_load($vocab_machine_name);

if (isset($vacab->vid)) {

  $vid = $vacab->vid;
  $terms = taxonomy_get_term_by_name('parent', $vocab_machine_name);
  $parent_term = array_pop($terms);

  // Create terms what needed.
  $term_names = array(
    'new term',
  );

  if (empty($terms) && isset($parent_term->tid)) {

    $parent_tid = $parent_term->tid;

    foreach ($term_names as $term_name) {
      $new_term = taxonomy_get_term_by_name($term_name);

      // Check if the term already exsists.
      if (empty($new_term)) {
        $new_term = new stdClass();
        $new_term->name = $term_name;
        $new_term->vid = $vid;
          $new_term->parent = $parent_tid;

        taxonomy_term_save($new_term);
      }
    }
  }
}