form_alter: Inline entity Form
IEF has a hook as outlined in the inline_entity_form.api.php file.  

/**
 * Perform alterations before an entity form is included in the IEF widget.
 *
 * @param $entity_form
 *   Nested array of form elements that comprise the entity form.
 * @param $form_state
 *   The form state of the parent form.
 */
function hook_inline_entity_form_entity_form_alter(&amp;$entity_form, &amp;$form_state) {
  if ($entity_form['#entity_type'] == 'commerce_line_item') {
    $entity_form['quantity']['#description'] = t('New quantity description.');
  }
}


Check the inline_entity_form.api.php file as there are a few hooks that you may be able to use.