Extends entity and repository - symfony

Question

I want to create some core for my Symfony app.
The composer create-project will be included my core provided by Github repository.
Structrue of project:
Symfony-project/
├─ app/
├─ src/
│ └─ AppBundle/
│ └─ Entity/
│ └─ Category
│ └─ Repository/
│ └─ CategoryRepository
├─ tests/
├─ var/
├─ vendor/
│ └─ core/
│ └─ src/
│ └─ bundles/
│ └─ Entity/
│ └─ Category
│ └─ Repository/
│ └─ CategoryRepository
└─ web/
I want extends vendor Entity and Repository by src/AppBundle Classes.
I used annotations inside Entity.
How did solve this problem?
I think about extend class by base category and mark is as final:
<?php
namespace AppBundle\Entity;
use Vendor\Namespace\Category as BaseCategory;
use Doctrine\ORM\Mapping as ORM;
/**
* #ORM\Entity
*/
final class Category extends BaseCategory
{
In next step add some rules inside app/config/config.yml e.g.
my_core:
extended_entities:
Vendor\Namespace\Category: AppBundle\Entity\Category
and use compillerpass to change metadata
About the Repository I think about the same thing as above or maybe register is as service(??)
But I think it's a little bit reckless and I'm looking for some clues how to do it better.