I've been trying to add a customer field to tpl_modules_opc_customer_info.php. I chased down all of the instances and added my field, but haven't had any luck storing it in checkout, nor the database.

I am calling the stored value on checkout success with an observer class for another application. I can't even get it stored in the session.

Do you have any idea or documentation for customer fields in guest checkout?

Thanks in advance