protected function getFormParent()
    {
        // If polymorphic relationship is actually defined, use it
        if ($this->FormID && $this->FormClass) {
            $formClass = $this->FormClass;
            return $formClass::get()->byID($this->FormID);
        }

        // Revert to checking for a form from the session
        // LeftAndMain::sessionNamespace is protected. @todo replace this with a non-deprecated equivalent.
        $sessionNamespace = $this->config()->get('session_namespace') ?: CMSMain::class;

        $formID = Controller::curr()->getRequest()->getSession()->get($sessionNamespace . '.currentPage');
        if ($formID) {
            return UserDefinedForm::get()->byID($formID);
        }
    }