Form posting before ajax can update content
function THEME_form_alter(&amp;$form, &amp;$form_state, $form_id) {
    $form['#validate'][] = 'webform_validate';
}

function webform_validate($form, &amp;$form_state) {
  //Appending comments field with campaignString
  $campaingString = $form_state['values']['submitted']['campaignstring'];
  $comments = $form_state['values']['submitted']['Comments'];
  $comments = "[".$campaingString."]  " . $comments;
  $form_state['values']['submitted']['Comments'] = $comments;
}