how to use function arg() in drupal to call .tpl files?
If I understand it correctly you are looking for a way to render .tpl.php files on certain paths, this article explains how to do it. 

In the article they define only one path and show you how to make sure a .tpl.php is rendered. You can easily adjust the code to make it work with 3 different paths and 3 different tpl.php files.

Hope this helps!