code: public function nestedFormSave($data, $form, $request)
      {
          $formAction = $this->getFormActionFromRequest($request);
          $actionName = $formAction->getButtonName();
  
          $this->record->$actionName($data, $form, $request);
  
          return Controller::curr()->redirectBack();
      }
docs: Handles the saving of the nested form. This is essentially a proxy method
  for the method that the BetterButtonNestedForm button has been configured
  to use
  
  @param  array $data    The form data
  @param  Form $form     The nested form object
  @param  HTTPRequest $request
  @return HTTPResponse