[Forums] Destination mixed with URL

I want that a set of screens are led to a certain screen preparation, and after that I want to be redirected to the initial page.
I'm currently doing that through an input paramenter (OriginalURL) and a ExternalURL, but I need to sent a paramenter to my initial page. I can do it through the URL, but I don't want to.
Is there a way of setting the destination screen using a variable?

Thanks in advance!