You can use the Nightjet with Couchette or Sleepers (reservation compulsory) or the Night IC (these are the seating coaches of the Nightjet on this Route and possible without reservation) ontop you can catch  ICE´s from Berlin to Mannheim or Basel with connection to Zürich at daytime :)

If you wanna catch some proper sleep, you should definitely opt for the sleeper/couchette in the Nightjet and not the seating car/night ICE.
Book some time in advance as sleepers and couchettes might sell out well ahead of time!
 

I want to book couchettes for my group who are travelling from Ljubljana to Munich on the 23:51 Nightjet from Ljubljana to Munich.

We all have Interrail Global Passes - how can I reserve couchettes for 12 people? I have tried online but I can’t find a place where I can do it. I have done this journey before and paid for the reservation - but I can’t see anywhere I can make the reservation now. 

David Burbidge, Sedbergh, Cumbria, UK

It should be possible on the ÖBB website if you split the booking into 6 + 6.