Pass form data to another form (forms are on different domains). With sessions

Question

So I have a sign up form on one domain. After completing sign up on that site user has to go to paysite and register there.

I want to save form data in session (when user registers on first site) and then fill it in 2nd form when users gets to it + auto submit.

1st page smth like this?

<?php
session_start();
if (isset($_POST['Submit'])) { 
$_session['login'] = $_POST['login'];
$_session['name'] = $_POST['name'];
$_session['mail'] = $_POST['mail'];
} 
?>

But what I have to put on 2nd?

Answer 1

I dont really understand what you are trying to do. But session cookies could only share by pages on the same domain. For passing cookies to another domain, you have to use post/get mothed.