editing campaign thru xml-editor

hi there, i hope hope you can give me some advice...

first of all: excuse my language, if i write anything wrong, i'm from poland and i don't speak perfect english.

ok my problem is this:
the campaign in cfs 3 "fortress europe" can be edited with an xml-editor. if you open the file, you see many informations like time dates and coordinates. what I tried to do was to change the frontline by changing the position coordinates under "frontline". I tried it several times but it never worked when I finally started the game normally and
I don't understand why.
is it possible at all to change the frontline (or any other campaign information) with an xml-editor?...and if yes, could you help me and tell me how? thank you...

Your English is fine, don't apologize.

See if this helps, the post 3rd from the bottom looks especially good.