title: Create form for multiple/two NOT related models in CakePHP
body: <p>I have two Models: ModelA, ModelB. They booth have id, name, ..., done(bool) fields.</p>
  
  <p>ModelA does NOT relate any way to ModelB!</p>
  
  <p>I created ONE Form, which have booth models fields in ModelA/add.ctp</p>
  
  <pre><code>echo $this-&gt;Form-&gt;create('ModelA', [
  ...
  ]);
  
  echo $this-&gt;Form-&gt;input('ModelA.name');
  ...
  echo $this-&gt;Form-&gt;input('ModelA.done', [
      'default' =&gt; true
  ]);
  
  
  echo $this-&gt;Form-&gt;input('ModelB.name');
  ...
  echo $this-&gt;Form-&gt;input('ModelB.done', [
      'default' =&gt; true
  ]);
  </code></pre>
  
  <p>My problem, is that Cake does not create a checkbox for ModelB.done instead a simple input field.
  Also it does not validates ModelB. (Because it does not know these fields relates to ModelB.)</p>
  
  <p>I can do manually validation, by loading ModelB in ModelA controller and do something like: <code>$this-&gt;ModelB-&gt;validate(...)</code></p>
  
  <p>My question is: Is it possible to set that this Form has two not related model?</p>