code: public void addChildForm(Form childForm) {
  		childForms.put(childForm.getId(), childForm);
  		getFormModel().addChild(childForm.getFormModel());
  	}
docs: Add a child (or sub) form to this form. Child forms will be tied in to
  the same validation results reporter as this form and they will be
  configured to control the same guarded object as this form.
  <p>
  Validation listeners are unique to a form, so calling
  {@link #addValidationListener(ValidationListener)} will only add a
  listener to this form. If you want to listen to the child forms, you will
  need to add a validation listener on each child form of interest.
  <p>
  <em>Note:</em> It is very important that the child form provided be
  created using a form model that is a child model of this form's form
  model. If this is not done, then commit and revert operations will not be
  properly delegated to the child form models.
  
  @param childForm to add