How to Add Menu Item to Parent Using Civix
Example:

/**
 * Implements hook_civicrm_navigationMenu().
 *
 * @link https://docs.civicrm.org/dev/en/latest/hooks/hook_civicrm_navigationMenu/
 */
function dmfactuurlink_civicrm_navigationMenu(&amp;$menu) {

  _dmfactuurlink_civix_insert_navigation_menu($menu, 'Administer', array(
    'label' =&gt; E::ts('Domus Medica Factuur Link Instellingen'),
    'name' =&gt; 'dmafctuurlink_setting',
    'url' =&gt; 'civicrm/dmfactuurlink/form/setting',
    'permission' =&gt; 'administer CiviCRM',
    'attributes' =&gt; [],
    'operator' =&gt; 'OR',
    'separator' =&gt; 0,
  ));
  _dmfactuurlink_civix_navigationMenu($menu);
}