REST API将公司链接到另一家公司FOSRestBundle

In a REST API that I'm developing a Company has a parent attribute which is also of the Company Class.

That way I can create a three of Companies. A Company has one parent Company (Company Class) and can have multiple children Companies (Collection)

/**
* @ORM\ManyToOne(targetEntity="Company", inversedBy="child")
* @Expose()
*/
protected $parent;

/**
* @ORM\OneToMany(targetEntity="Company", mappedBy="parent")
*/
protected $child;

public function __construct()
{
    ...
    $this->child = new \Doctrine\Common\Collections\ArrayCollection();
}

How would I go about and make/remove that relationship of parents and children companies?

I've read about the LINK verb but I'm afraid it's not supported by all webservers.

Should I set the relationship with PUT? How would I then remove the relationship to the parent (set it to NULL).

My CompanyController looks like this:

/**
    * Edit Action
    * 
    * @Rest\View()
    */
   public function editAction(Company $company)
   {
       return $this->processForm($company);
   }

   /**
    * Remove Action
    * 
    * @Rest\View(statusCode=204)
    */
   public function removeAction(Company $company)
   {
        $em = $this->getDoctrine()->getManager();
        $em->remove($company);
        $em->flush();
   }
   /**
    * ProcessForm Action
    */
   private function processForm(Company $company)
   {

       $statusCode = $this->getRequest()->getMethod() == 'POST' ? Codes::HTTP_CREATED : Codes::HTTP_SEE_OTHER;

       $form = $this->createForm(new CompanyType(), $company);
       $form->bind($this->getRequest());

       if($form->isValid())
       {
           $em = $this->getDoctrine()->getManager();
           $em->persist($company);
           $em->flush();

           return $this->redirectView(
            $this->generateUrl(
                'company_get',
                array('id' => $company->getId())
            ),
            $statusCode
            );

       }

       return View::create($form, 400);
   }

Any suggestions?