include url call on a third party site

[macdar]

here's the deal:

I have a website already running, that consists of whole bunch of script:

chat.php, register.php, profile.php, etc, etc..

and I access it by typing www.mydomain.com/chat.php

but I'd liek to create a service for other gigs so that they take advantage of my app, by pasting a simple URL, like:

include("http://partner.mydomain.com/index.php?s=SESSIONID&p=PARTNERID....etc..");

ok, so whats the big deal ? they have already included my app, right?
the problem is, the chat has embedded links (ie people's nickname are linked to their profiles). so when someone clicks on the link, it would actually lead to my site.
But I don't want that. I'd like people to think they are still on the same site. I need just to retrieve content from my site.

I don't wanna rewrite my existing code, instead I want to prepare environment before any code is executed. that's where auto_prepend and auto_append come into play. and that's where I got stuck;) I mean I tried with fopen, but that's not the way to go (broken links etc..)

I think I would have to get affiliate's URL from query,
go get content (ie chat), and redirect it back at the affiliate address with the content embedded to it. Is this possible to do that?