Displaying taxonomy term list within another taxonomy term
Dee, I completely did not understand your question. But these code might help you.

/*To load a vocabulary*/

 $vocabulary = taxonomy_vocabulary_machine_name_load($machine_name);
 Example::$vocabulary = taxonomy_vocabulary_machine_name_load('book');

/*To get array of all term objects as a tree*/

$terms = taxonomy_get_tree($vocabulary);

/*To get children of all terms*/


foreach($term as $aterm) {

  $child = taxonomy_get_children($aterm);

}