How may I 'trick' $ajax->observeField into firing with linked combo boxes?

After hours of research and trial and error, I must turn to the group
for help with this. I have a series of three linked combo boxes for
state, county, and city from the tutorial here:
http://forum.phpsitesolutions.com/php-frameworks/cakephp/ajax-cakephp-dynamically-populate-html-select-dropdown-box-t29.html.

They work great... mostly. I have added to the code in the add.ctp
file to include an 'empty' element of 'Please select a [whatever]'. So
all three combo boxes start out with the first value being 'Please
select a [whatever]'.

The user selects a state. The $ajax->observeField on the state combo
box fires and loads the county combo box. This loses the initial
'Please select a [whatever] and displays the first entry in the list
of counties for the selected state.

Even if the user opens the county combo box and selects the first
entry, the $ajax->observeField does not fire to load the next combo
box of cities, probably because there is no actual change. Only if the
user selects a DIFFERENT element than the first one does the event
fire.

A possible way around this is to still have the 'Please select a
[whatever]' as the first element in the county combo box, forcing the
user to make another selection and thus firing the next observeField
trigger to load the cities applicable for a selected county.

How do I do that? How do I force another 'Please select a [whatever]
element into the list that is returned from the controller function to
retrieve the counties for the selected state?

Here are some code snippets:

/app/controllers/examples_controller.php

function getCounties() {
$this->set('options',
$this->Example->County->find('list',
array(
'conditions' => array(
'County.state_id' => $this->data['Example']['state_id']
),
'group' => array('County.name')
)
)
);
$this->render('/examples/ajax_dropdown');
}

function add() {
if (!empty($this->data)) {
$this->Example->create();
if ($this->Example->save($this->data)) {
$this->Session->setFlash(__('The Example has been saved', true));
$this->redirect(array('action'=>'index'));
} else {
$this->Session->setFlash(__('The Example could not be saved.
Please, try again.', true));
}
}
$cities = array();
$counties = array();
$states = $this->Example->State->find('list');
$this->set(compact('cities', 'counties', 'states'));
}

/app/views/examples/add.ctp

<?php
echo $form->input(
'state_id',
array(
'options' => $states,
'empty' => 'Please select a state'
),
null,
array(
'id' => 'states',
'label' => 'State'
)
);
echo $form->input(
'county_id',
array(
'options' => $counties,
'empty' => 'Please select a county'
),
null,
array(
'id' => 'counties',
'label' => 'County'
)
);
$options = array('url' => 'getcounties', 'update' =>
'ExampleCountyId');
echo $ajax->observeField('ExampleStateId', $options);

Thank you in advance for your kind assistance.
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