How to force a page into an iframe...but?

I have a bit of a problem. I have build my website around an iFrame. There are two different versions...ala two different home pages (index.php and home.php) depending upon which version you choose at a splash screen (highband or lowband).

Here's the problem. I need to make all of the child pages incapable of being viewed outside of it's intended iFrame. The problem is, if I use the standard Javascript for forceing a page into it's intended iFrame then I can't also let it be viewable in the alternate iFrame, depending upon user choice.

Is there a way for the script to point to a default parent page but allow the child page to also be viewed in the alternate parent? So, if you found the page outside of my site it would always load the page into the default parent page. But if you came in the front door of my site, via the splash page you would have the option to view that same file within either of the parent pages...depending upon choice (highband or lowband).

Is that clear???

Thanks

 

Perhaps the easiest approach would be to check where someone has come from in the HTTP Referer in the headers.

From that you can direct them where you like - so, for example if they have come from yourdomain.com you can proceed as normal, and if they have come from somewhereonthe.net you can redirect them to a page of your choice.

Downsides to this approach would be not all user agents return headers, and they can be (reasonably) easily altered / spoofed by users if they desired so it's not a fail safe / secure solution, but it would work the vast majority of times in a low security environment.