Configuring form builder clinical forms and enable to change patient visit type from registration page.

I guess I have understood the problem that you’re facing with the AddMore section along with ControlEvents.

When you’re working with AddMore, use form.getFromParent instead of form.get.

Please see the sample code snippet for your use case.

function(form) {
  if (form.getFromParent('immunization').getValue() === 'BCG') {
    form.getFromParent('BCG Number of Immunization').setHidden(false);
  } else {
    form.getFromParent('BCG Number of Immunization').hideAndClear();
  }
}

Related talk thread - Rendering of addmore section or obsgroup is not working as expected when there are form conditions inside it - #3 by angshuonline