How can I enable a custom template to create cck based content types?

Hi,

I need your help in enabling different templates for creating node of custom cck types.

I have created 3 custom cck types.

cck_content_type1
cck_content_type2
cck_content_type3

I need to have three different custom templates to create each type of content.

I created three template files with names below and placed them in my custom theme named customTheme, which is based on garland.

node-add_cck_content_type1.tpl.php
node-add_cck_content_type2.tpl.php
node-add_cck_content_type3.tpl.php

I understand that the naming of template is may not be correct.

I am not sure how i can let the system know that these templates should be used for creating content of repective node types.

One thing i would not want to do is create multiple copy of page.tpl.php.
This would require me to change all these files everytime i make simple change to main layout through page.tpl.php

Appreciate your help.