Symfony2 FOSUserBundle merge resetPasswordform with custom form

I am trying to create a form by merging 2 form types as following.

Teacher Entity that has a one to one relation with User Entity.

I am using FOSUserBundle and i want to merge the ResettingFormType with my custom TeacherFormType, to end up with a form that both fields from my custom & fos reset password form.

1- Teacher Entity:

/**
 * @var \User
 * 
 * @ORM\OneToOne(targetEntity="ITJari\UserBundle\Entity\User", fetch="EAGER")
 * @ORM\JoinColumn(name="user_id", referencedColumnName="id")
 * 
 */
private $user;

public function getUser() {
    return $this->user;
}


public function setUser($user) {
    $this->user = $user;
    return $this;
}

2- Extending FOS Reset password:

namespace ITJari\SchoolBundle\Form\Type;

use Symfony\Component\Form\AbstractType;
use Symfony\Component\Form\FormBuilderInterface;

class ResettingFormType extends AbstractType {

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

    }

    public function getParent() {
        return 'fos_user_resetting';
    }

    public function getName() {
        return 'ragab';
    }

}

3- Teacher Form Type

namespace ITJari\SchoolBundle\Form\Type;

use Symfony\Component\Form\AbstractType;
use Symfony\Component\Form\FormBuilderInterface;
use Symfony\Component\OptionsResolver\OptionsResolverInterface;

class TeacherFormType extends AbstractType {

    public function buildForm(FormBuilderInterface $builder, array $options) {
    }

    public function setDefaultOptions(OptionsResolverInterface $resolver) {
        $resolver->setDefaults(array(
            'data_class' => 'ITJari\SchoolBundle\Entity\Teacher',
        ));
    }

    public function getParent() {
        return 'fos_user_resetting';
    }

    public function getName() {
        return 'teacherform';
    }

}

4- In controller:

$teacher = new \ITJari\SchoolBundle\Entity\Teacher();
$teacher->setUser($user);
$form = $this->createForm('teacherform', $teacher); 

But i got the following error:

Neither the property "plainPassword" nor one of the methods "getPlainPassword()", "isPlainPassword()", "hasPlainPassword()", "__get()" exist and have public access in class "ITJari\SchoolBundle\Entity\Teacher". 500 Internal Server Error - NoSuchPropertyException