Load Parent Product on ProductPage in Shopware 6

Ressources => config => config.xml

<?xml version="1.0" ?>

<container xmlns="http://symfony.com/schema/dic/services"
           xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
           xsi:schemaLocation="http://symfony.com/schema/dic/services http://symfony.com/schema/dic/services/services-1.0.xsd">

    <services>
        <service id="MY_Shortdesc\Subscriber\ProductPageSubscriber">
            <argument type="service" id="product.repository"/>
            <tag name="kernel.event_subscriber"/>
        </service>
    </services>
</container>

Subscriber => ProductPageSubscriber.php

<?php declare(strict_types=1);

namespace MY_Shortdesc\Subscriber;

use Shopware\Core\Framework\DataAbstractionLayer\EntityCollection;
use Shopware\Core\Framework\DataAbstractionLayer\EntityRepositoryInterface;
use Shopware\Core\Framework\DataAbstractionLayer\Search\Criteria;
use Shopware\Storefront\Page\Product\ProductPageLoadedEvent;
use Symfony\Component\EventDispatcher\EventSubscriberInterface;

class ProductPageSubscriber implements EventSubscriberInterface
{
    /**
     * @var EntityRepositoryInterface
     */
    private $productRepository;

    public function __construct(EntityRepositoryInterface $productRepository)
    {
        $this->productRepository = $productRepository;
    }

    public static function getSubscribedEvents(): array
    {
        return [
            ProductPageLoadedEvent::class => "onProductsLoaded"
        ];
    }

    public function onProductsLoaded(ProductPageLoadedEvent $event)
    {
        if (!$event->getPage()->getExtension("parentProduct")) {
            /** @var EntityCollection $parent */
            $parent = $this->productRepository->search(
                new Criteria([
                    $event->getPage()->getProduct()->getParentId()
                ]), $event->getContext()
            )->first();
            $event->getPage()->addExtension("parentProduct", $parent);
        }
    }
}

There is another way without adding a extra query and without using an extension:

    public static function getSubscribedEvents(): array
    {
        return [
            ProductLoaderCriteriaEvent::class => "onProductLoad"
        ];
    }

    public function onProductLoad(ProductLoaderCriteriaEvent $event)
    {
        $event->getCriteria()->addAssociation('parent');
    }

(untestet)

    public function onProductLoad(ProductLoaderCriteriaEvent $event)
    {
        $event->getCriteria()->addAssociation('parent');
    }

This gives me this error:

The given alias '`product.parent.translation`' is not unique in FROM and JOIN clause table. The currently registered aliases are: `product`, `product.parent`, `product.translation`, `product.tax`, `product.manufacturer`, `product.cover`, `product.unit`, `product.deliveryTime`, `product.parent.translation`, `product.parent.parent`.

I tried both $event->getCriteria()->addAssociation('product.parent.parent'); and $event->getCriteria()->addAssociation('product.parent');. I both cases the product's parent keeps null :(

I tried both $event->getCriteria()->addAssociation('product.parent.parent'); and $event->getCriteria()->addAssociation('product.parent');. I both cases the product's parent keeps null :(

Same for me.