how display multiple files as one movie?

[lukasitaly]

does it have to transcode?

No it doesn't have to transcode. It's easy, download MKVToolNix from https://mkvtoolnix.download/downloads.html (scroll down to windows), then

1.     Open MKVToolNix's GUI version.
   
2.     Click on "Add source files" and select the parts of the movie you want to merge.
   
3.     Arrange the files in the desired order if needed.
   
4.     Choose an output location and filename for the merged file.
   
5.     Click "Start multiplexing" to merge the files.
   

With MKVToolNix, you can also easily add or remove subtitles and audio tracks. Personally, I use it to get rid of subtitles in languages I don't understand, keeping things organized.

I hope this helps. If you need anything else, just let me know.