Function which pushes an array element after specified key. Note that array is not catched as reference. You need to re-set your array when using this function.

array_push_after_key.php

function array_push_after_key($array, $key, $var) {
  $new_array = array();
  foreach ($array as $k => $v) {
    $new_array[$k] = $v;
    if ($k === $key) {
      foreach ($var => $kk => $vv) {
        $new_array[$kk] = $vv;
      }
      break;
    }
  }
  return $new_array;
}