Symfony2 FOS用户在表单中有多个地址

Question

When a company registers they insert his main office adress data. This data is simply saved in a USer entity. However, If the company has more offices he should be able to add them on the same form, but to a different entity. Is that even possible? If not, what are the options.

For example:

When a user goes to registration the form opens:

public function buildForm(FormBuilderInterface $builder, array $options)
{
    parent::buildForm($builder, $options);
    $builder

        ->add('country', 'country', array(
            'label' => 'form.label.country',
            'required' => false,
        ))
        ->add('town', 'text', array(
            'label' => 'form.label.town',
            'required' => false,
        ))

        >add('residence', 'text', array(
            'label' => 'form.label.adress',
            'required' => false,
        ))
        ->add('zip', 'text', array(
            'label' => 'form.label.zip',
            'required' => false,
        ))

This is saved in a User class.

If a user has more offices additional fields should appear that store the new data to a different entity.

UserAdress entity:

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

    /**
     * @var integer
     *
     * @ORM\Column(name="id_user", type="integer")
     */
    private $idUser;

    /**
     * @var string
     *
     * @ORM\Column(name="office_name", type="string", length=255)
     */
    private $officeName;

    /**
     * @var string
     *
     * @ORM\Column(name="Adress", type="string", length=255)
     */
    private $adress;

    /**
     * @var string
     *
     * @ORM\Column(name="country", type="string", length=255)
     */
    private $country;

    /**
     * @var string
     *
     * @ORM\Column(name="town", type="string", length=255)
     */
    private $town;

    /**
     * @var string
     *
     * @ORM\Column(name="zip", type="string", length=255)
     */
    private $zip;

Now I need to render a new form with these fields in the same registration form... Is that possible?