Extend form view (Cake/2.5)

Need Help
1

In my plugin I need two views for the “Create new” and “Edit existing” features which are 95% identical so I decided to play with extending views. So I create a common view with the complete form:

echo $this->Form->create('FooManager.user');
echo $this->Form->hidden('id');
echo $this->fetch('new_user_fields');
echo $this->Form->input('full_name');
echo $this->Form->end();

… and then a child view for the “Create new” action:

$this->extend('FooManager.Common/user_form');
$this->append('new_user_fields');
echo $this->Form->input('login');
$this->end();

However, form fields in the child view do not get populated automagically from $this->request->data as fields in parent view do. Is it a known limitation or am I doing something wrong?