Delete related records after update/save

I hav two models.

namespace Manager\Models;
use Phalcon\Mvc\Model;
use Phalcon\Mvc\Model\Validator\Uniqueness;
class Aliases extends Model
{
    public $id;
    public $name;
    public $description;
    public $aliastypeId;
    public function validation()
    {
        $this->validate(new Uniqueness(array(
            "field" => "name",
            "message" => "The alias is already registered"
        )));
        return $this->validationHasFailed() != true;
    }
    public function initialize()
    {
        $this->hasMany('id', 'Manager\Models\AliasesContent', 'aliasId', array(
            'alias' => 'aliasescontent',
            'reusable' => true
        ));
    }
}

namespace Manager\Models;
use Phalcon\Mvc\Model;
class AliasesContent extends Model
{
    public $id;
    public $content;
    public $aliasId;
    public function initialize()
    {
        $this->belongsTo('aliasId', 'Manager\Models\Aliases', 'id', array(
            'alias' => 'aliases',
            'reusable' => true
        ));
    }
}

When I edit a "Aliases" and saved, I have to remove all the contents of the table "AliasesContent" referring to "AliasesContent.aliasId" to re-enter the new content.

public function editAction($id)
{
if ($this->request->isPost()) {
   $aliases->assign(array(
      'name' =>$this->request->getPost('name', 'striptags'),
      'description' => $this->request->getPost('description', 'striptags')
   ));

   // Delete the entire contents of the related table.
   AliasesContent::find('aliasId IN ('.$id.')')->delete();
   // ------------

   $aliasContentPost = $this->request->getPost('aliascontent');
   $aliascontent = array();
   foreach ($aliasContentPost as $key => $value) {
      $aliascontent[$key] = new AliasesContent();
      $aliascontent[$key]->content = $value;
   }
   $aliases->AliasesContent = $aliascontent;
   if (!$aliases->save()) {
      $this->flash->error($aliases->getMessages());
   } else {
      $this->flash->success("Alias was updated successfully");
   }
}

The problem is that if the update/save fails the validation name (Uniqueness) present in the model, the related table records are deleted and new records are not inserted.

I do not want to update only the difference, I need to be removed all records in the related table and reinsert the new records, after validation of the main table "Aliases".

Thanks for any help.