Alter many forms from theme

Dear all,

I want to theme the webform form a bit, and therefore I would like to change all forms. Unfortunate the form id has an id attached to it:
webform_client_form_1
webform_client_form_2
webform_client_form_3

I want to change something in the theme for all of these forms. Normally I would do something like:

[code]
/* CHANGE NEWSLETTER FORM */
function MYTHEME_theme() {
return array(
'simplenews_block_form' => array(
'arguments' => array('form' => null),
),
);
}

function MYTHEME_simplenews_block_form($form) {
if ($form['action']['#type'] == 'radios') {
$form['action'] = array(
'#type' => 'hidden',
'#value' => 'subscribe',
);
}
return drupal_render($form);
}
[/code]

But it is impossible to add a number for each form. How to solve this problem?

Regards,

Geert