Magento costum product that is like bundle

I am making a modul Petka/BundleOverride and I want to make a new product tpye from it. I already made something but, the problem that is doesn’t have “Add Options” under the Bundle Items tab. The element is probably shown only when it senese that it is bundle that it is open. But I also want it. How can I do it…
This is what I have:
etc/product_types.xml

<?xml version="1.0"?>
<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:module:Magento_Catalog:etc/product_types.xsd">
    <type  name="petka_bundle"  label="Petka Bundle"  modelInstance="PetkaBundleOverrideModelProductTypeNewProductType"  composite="true"  isQty="true"  sortOrder="120" />
</config>

NewProductType.php

<?php

namespace PetkaBundleOverrideModelProductType;

use MagentoBundleModelProductType as BundleType;

class NewProductType extends BundleType {}