If I use prosper202, I can't change the destination URL later on if I want to change the offer. Prosper202 will provide me with the PHP redirect code, but how do I change the subids for each ad? For example, if my destination URL is domain.com/test.php, and I put the PHP redirect code that prosper202 gives me in there, when someone clicks that ad, how do I tell which ad was clicked, if they are all going to the same test.php and redrecting through the same link?