How to Modify Advanced Guestbook Navigation?

I use a container-file on my site, that includes the required files.
(example: if i call container.php?id=guestbook, the guestbook will be opened, but inside the container file) all that works perfectly, the entries are listed where they should but after all I've got a problem:
I want to modify the navigation (jumping to the next page) in that way, that klicking on the "next page" link wont bring me to "container.php?entry=x" (thats how it is now, because of the include), but I want the script to call "container.php?id=guestbook&entry=x"

i wasnt able to find out which variable to change, so who can help me?

Oh:

take a look at:
http://www.screech.de/new/guestbook/container.php?id=guestbook
to understand my problem better