I am new to modding for Zen Cart, but have experience modding for phpbb3.

My Zen Cart mod will need to perform extra actions using the info from the form fields when a new user registers (create_account.php) and when a user changes their account info (I've created a new module/pages/mymod folder and a tpl_mymod_default.php for this part).

For the action that happens on new user registration will I need to modify the core files or can I create a separate file somewhere that can be loaded between create_account and create_account_success?