Yeah well I thought of either not touching the tracks provided by Harmy, or including one track of each edition.

Video wise, problem is, I thought I found a free software for doing that, I just didn't understood they meant it was doing an mkv FROM a disc with branching, not permitting of creating one. But I think I might be able to achieve that from Mkvtoolnix, but it seems VERY complicated as it apparently can assign a clip to a certain language but I have no clue on how to get the extra files necessary for achieving that. And not to mention I don't know if such an mkv would keep its properties after being muxed into a Blu-ray. Any video geek to help?

Or I could buy Scenarist... Which would require selling my house :p

EDIT: Google found this, but there will be lag between scenes, which is better than nothing.