Custom node Template for script tags
Instead of adding three template files for three nodes with the same content in it in my opinion will be a better solution to add the JS file conditionally using drupal_add_js

For eg:



 $allowed_nid = array(28, 1212, 38);
 if(in_array(arg(1), $allowed_nid)){
  drupal_add_js("http://www.examp.com/scripts/invitation.ashx?company=4444", "external");
 }



You can add the snippet in a hook_init function in any of your custom modules. (Best is add in a custom utility module which hold all general function to be used throughout.)
Else you can add it in your theme's template.php in the template_preprocess_page function.