I will use a 3rd party payment solution. The reason is, I want that the user have to choose at the registration process a subscription and pay for it at the same process like the registration. There is no possibility to create an account if the user didn't pay for it. So I renamed the file tpl-registration.php that the classipress build in registration don't appear anymore. What I want now is, to forward the user, when he/she clicks on registration, to a internal sales page. In which .php-file can I find the inbuild classipress register redirection?