Moda.php

<?php
//view
// view Users/cadastro.ctp

$this->Form->create(false,array('controller'=>'designers','action'=>'register'));
$this->Form->input('whatever');
$this->Form->submit('save');
$this->Form->end();

$this->Form->create(false,array('controller'=>'users','action'=>'register'));
$this->Form->input('whatever');
$this->Form->submit('save');
$this->Form->end();

?>

<?php 
//Controller Designers

public $uses = array('Designer','User')

public function register(){
  
  $this->User->save($data);
$this->render('view');
  
  }
  
  //some tables using here
  
//Controller User

public $uses = array('User')

public function register(){
  
  $this->User->save($data);
$this->render('view');  
  }

//A view pode ter qualquer nome, mesmo que ela não tenha um método para ela

?>