Problem with Stacking: doesn't work in library

Hello forum,

I have a problem I wasn't able to solve by myself (or with searching/wikis).

I have my movies organized in folders with one folder for each movie.
But in those folders are also files for trailers or additional features like:

MovieA (Folder)
- MovieA - Trailershow1 (file)
- MovieA - Trailershow2 (file)
- MovieA - MainMovie (file)
- MovieA - MakingOf (file)

So now I want that the library only has an entry for MovieA and when I start it it should play those files in order as they are in the folder.

I searched a while and found that this task could be done with file stacking.
So I tried a bit with file stacking and reg-ex to get a scheme for my specific structure.
Now when I browse the folder and enable to stack files, everything looks as I expected:
One entry for MovieA and when I start it plays the files in the order they were in the folder.

Now comes the part I do not understand:
In movie/library mode the movie parts DON'T get stacked - I get 4 entries for the above example.
But everything I found about this topic is that if files get stacked in file mode they are automatically treated as ONE move in the library.

Am I missing something or did I get something wrong?
How can I achieve that I only get one entry "MovieA" in library mode?
Or is there an other - maybe better way to organize such a scenario?

Help an hints welcome.
Even when I think it has nothing to do with the operating system: I use Win7 64bit and Frodo RC1 (und 11 I had the same problem)

Thanks and greetings,

Nickname777