CakePHP use Hash to prepare Model array for saving - php

Question

I'm wondering how one might use CakePHP Hash functions to achieve the following:
This is the array before (Plugin stored in Session):
$Data = array(
'add' => array(
'Certificate' => array(
'name' => '',
'entity_id' => '1',
'state_id' => '18',
'domicile' => '',
'formation_date' => array(
'month' => '',
'day' => '',
'year' => ''
)
)
),
'add2' => array(
'Certificate' => array(
'filing_fees' => '82'
)
)
)
This is the array after. I am reformatting it to call Certificate->save(). I removed the top level and merged the Certificate model.
$Data = array(
'Certificate' => array(
'name' => '',
'entity_id' => '1',
'state_id' => '18',
'domicile' => '',
'formation_date' => array(
'month' => '',
'day' => '',
'year' => ''
),
'filing_fees' => '82'
)
)
This is my current code:
$processed = array();
foreach ($Data as $k => $array1) {
foreach ($array1 as $array1k => $array2) {
if (!isset($processed[$array1k])) {
$processed[$array1k] = array();
}
foreach ($array2 as $a2k => $a2v) {
$processed[$array1k][$a2k] = $a2v;
}
}
}
What I have works, but it's not very "Cake-ish" and will certainly cause problems when I need to prepare data for saving more complex model relationships (e.g. HABTM saveall).
I tried Hash::combine, Hash::merge, array_merge_recursive(), and combinations of these before posting. I understand the PHP logic, but I am lost to find the CakePHP functions with similar logic.
The first step is to merge the Model, then the second step is to remove the key ('add, 'add2'). The closest I got was Hash::combine, but there was no way to reference a $keyPath {s} of the Model, skipping over the first level ('add', 'add2') of the array.
If you could point me in the direction of which Hash or other CakePHP functions are recommended, I'd be happy to take the next step.