We want to be able to insert a tracking code into a url on another web page. Here is how we see it operating. We provide a url to an affiliate. http://example.com/register/&aff_id=123456 or something like that.
When the visitor gets to that url [url removed, login to view] there will be a form loaded into an Iframe there on that page. The form has its own unique url and an aff_id= in the url. We wanted to be able to replace the aff_id in the form with the aff_id=123456 that is coming from the http://example.com/register/&aff_id=123456
So the aff_id in the form url needs to be replaced with the aff_id from the url that the visitor originated from