src/Controllers/BetterButtonsNestedFormRequest.php
public function Form()
    {
        $formAction = $this->getFormActionFromRequest($this->request);
        $fields = $formAction->getFields();
        $fields->push(HiddenField::create('action', '', $formAction->getButtonName()));

        $form = Form::create(
            $this,
            'Form',
            $fields,
            FieldList::create(
                FormAction::create('nestedFormSave', 'Save')
            )
        );

        return $form;
    }
public function Form()
    {
        $formAction = $this->getFormActionFromRequest($this->request);
        $fields = $formAction->getFields();
        $fields->push(HiddenField::create('action', '', $formAction->getButtonName()));

        $form = Form::create(
            $this,
            'Form',
            $fields,
            FieldList::create(
                FormAction::create('nestedFormSave', 'Save')
            )
        );

        return $form;
    }
Create the nested form

@return  Form