Add subitem to second level

Question

I have primary links created manually. The are links to node (content type 'page') like

-About
--About Us
--About company

I need to add subitems About/About company/company1 and About/About company/company2 from my module.

Next lines create menu item in first level (in one level with -About)

$items['about2'] = array(
  'menu_name' => 'primary-links',
  'title' => 'About2',
  'page callback' => 'ninegm_about2',
  'access callback' => TRUE,
  'weight' => -10,
);