AdminController.php

<?php

[...]

     /**
     * @Extra\Route("/offer/{offerId}/creative", name="admin_offer_creative")
     * @Extra\Route("/offer/{offerId}/creative/{creativeId}", name="admin_offer_creative_edit")
     * @Extra\Template()
     */
    public function creativeAction($offerId = null, $creativeId = null)
    {
        // Get Offer
        $offer = $this->_getObject('Offer', $offerId);

        if (null === $offer->getId()) throw new NotFoundHttpException('The page you requested does not exist!');

        // Get Creative
        $creative = $this->_getObject('Creative', $creativeId);

        // Set offer to creative
        $creative->setOffer($offer);

        // Get form and handler
        $form = $this->get('form.factory')->create(new Form\CreativeType(), $creative);
        $formHandler = $this->get('form.handler')->create(new Form\CreativeHandler(), $form);

        [...]
    }

    protected function _getObject($entityName, $id = null)
    {
        // Find object
        if (null !== $id) {
            if (!$object = $this->get('doctrine')->getEntityManager()->find('ZGOffersMainBundle:' . $entityName, $id)) {
                throw new NotFoundHttpException('The page you requested does not exist!');
            }

            return $object;
        }

        // Initialize new object
        $entityName = 'JStout\MainBundle\Entity\\' . $entityName;
        if (class_exists($entityName)) {
            return new $entityName();
        }

        throw new NotFoundHttpException('The page you requested does not exist!');
    }

    [...]

Creative.php

<?php

[...]

class Creative
{
    /**
     * @ORM\Column(type="integer")
     * @ORM\Id
     * @ORM\GeneratedValue(strategy="IDENTITY")
     */
    protected $id;

    /**
     * @ORM\ManyToOne(targetEntity="Offer", cascade={"persist"})
     */
    protected $offer;

    /**
     * @ORM\OneToMany(targetEntity="CreativeQuestion", mappedBy="creative", cascade={"persist"})
     */
    protected $creativeQuestions;

[...]

CreativeQuestion.php

<?php

[...]

class CreativeQuestion
{
    /**
     * @ORM\Column(type="integer")
     * @ORM\Id
     * @ORM\GeneratedValue(strategy="IDENTITY")
     */
    protected $id;

    /**
     * @ORM\ManyToOne(targetEntity="Creative", cascade={"persist"})
     */
    protected $creative;

    /**
     * @ORM\ManyToOne(targetEntity="Question", cascade={"persist"})
     */
    protected $question;

    /**
     * @ORM\Column(type="integer")
     */
    protected $pos;

[...]

CreativeType.php

<?php

namespace JStout\MainBundle\Form;

use Symfony\Component\Form\AbstractType,
    Symfony\Component\Form\FormBuilder;

class CreativeType extends AbstractType
{
    public function buildForm(FormBuilder $builder, array $options)
    {
        $builder
            ->add('name')
            ->add('title')
            ->add('description')
            ->add('body')
            ->add('body')
            ->add('script')
            ->add('creativeQuestions') // how do i populate list with "Questions" then insert into creative_question?
            ->add('active');
    }

    public function getDefaultOptions(array $options)
    {
        return array(
            'data_class' => 'JStout\MainBundle\Entity\Creative'
        );
    }
}