Sonata Admin - change order parent categories

In my webapplication I have the following category structure:

<?php

namespace AppBundle\Entity;

use Doctrine\ORM\Mapping as ORM;

/**
 * Category
 *
 * @ORM\Table(name="category", indexes={@ORM\Index(name="fk_category_category_idx", columns={"parent_category_id"})})
 * @ORM\Entity(repositoryClass="AppBundle\Repository\CategoryRepository")
 */
class Category
{
    /**
     * @var string
     *
     * @ORM\Column(name="name", type="string", length=255, nullable=false)
     */
    private $name;

    /**
     * @var boolean
     *
     * @ORM\Column(name="enabled", type="boolean", nullable=false)
     */
    private $enabled = true;

    /**
     * @var integer
     *
     * @ORM\Column(name="id", type="integer")
     * @ORM\Id
     * @ORM\GeneratedValue(strategy="IDENTITY")
     */
    private $id;

    /**
     * @var \AppBundle\Entity\Category
     *
     * @ORM\ManyToOne(targetEntity="AppBundle\Entity\Category")
     * @ORM\JoinColumns({
     *   @ORM\JoinColumn(name="parent_category_id", referencedColumnName="id")
     * })
     */
    private $parentCategory;
}

A category can be a parent category or a subcategory of a parent.

Now I would like to add the possibility to change the order of display of only the parent categories.

How could this easily in Sonata Admin?

from Sonata Admin - change order parent categories