or generally the how to find Couchette end sleeper ?

I get connections with the night jet on DB. But that is with the night train leaving Köln just before midnight, which not might be a good idea when you have a small child. 

I suggest you check trains between Kolding and Hamburg. Then there is a night train between Hamburg and Zürich. In Zürich you take another train to Sargans.

I will try that. 

But generally on DB how to find out if the trains has like compartments with places to lie down? 

I found something like that 

https://www.international-bahn.de/de/upsale/1448678207?token=1ca24cb2e717577dc7dbc789

but i am not sure if the price of 199 euro for 4 person includes the berths? or first the price of 544 includes the berths? My understanding is that “Privatabteil Liegewagen” should include berths, but if so, then why so big price different?

@viking The night jets are run by ÖBB, not by DB. From DB you can buy seats on some night trains but for the sleepers and couchettes you need to look at ÖBB.

It does. It should also be possible to get Hamburg - Zürich for that price, unless the coaches to Zürich are already full (half the train only goes to Basel). I do see it on tickets.oebb.at: 3 adults and 1 child Hamburg - Zürich for €199.

This is the price for a private couchette compartment for up to three adults (you may add kids for free). 

But this is the price for a ticket and a reservation. So you won't need a railpass if you'd book this offer (at least for this part of your journey).

By the way, there's no difference if you'd book this offer with DB (which is possible even for couchette and sleeper) or ÖBB directly - you'll get the same tickets. In fact, even the DB booking is an ÖBB booking...

Thank you all for your answers.

1. I got confused, I will later try to book on obb and compare with db.
   i am not familiar with  the professional vocabulary. Private couchette compartment does it mean that the 4 of us will be the only passenger in this Abteil ( do not know the english name ) or we can still get extra 2 person and will there be 4 or 6 berths / beds in such a Abteil?
2. What is different between Privatabteil Liegewagen for 199 eu and Liegeplatz im Abteil mit 6 Liegen for 554 eu? For me it seems the same
3. Where can I see how these Abteilen look like?
4. Regarding interrail passes. Is the price always the same in particular year or maybe sometimes one can get it maybe cheaper on special?

t1]

Regarding just the booking of a sleeper or couchette compartment for the nighttrain (as shown in your own post), there’s no need to compare. DB is booking the night train with ÖBB booking system, so there’s no difference. 

Private means private. I don’t think this is misleading. It’s a private compartment (= Abteil) just for you. No other people are allowed to join.

There are 6 berths. But it’s possible to keep two of them folded away so you’ll also get a configuration with just 4 beds in the same compartment - you’ll see how it looks like following the link l3].

i2]

It’s not the same. A Privatabteil is private (no other person may join), Liegeplatz im Abteil mit 6 Liegen means that there are two (if you pay for your child) or three other people (if you don’t pay for your child) that may get booked in your compartment - it’s not private. So the cheaper offer is the better one. But for the date shown in your post there’s just one compartement left for 199 € - if someone books it, it’s gone - it’s just a special offer. But remember again: if you’ll buy an interrail pass, it would be complete nonsense to buy any of these offers. Both offers are complete tickets (ticket and reservation) for which you won’t need an interrail pass. 

�3]

The train operators website does show it: Couchette - Nightjet

t4]

The price of the interrail pass itself is not the same (normally, there are special offers every year - but the last one did just end last week). 

thank you Hector,

1. I am aware that I do not need the pass in case I buy these tickets. I was just asking for the pass maybe for the summer holiday. 
2. But if I would have the pass, then I would still have to pay the 199 for the private compartment or another amount?
3. The special offers were much better then the regular? Are there any particular times of the year when they make the special offers?
4. What is the different between private compartment in 1 and 2 class?

And one more. what is the different between interrail and eurail?

Interrail is for persons living in Europe, Eurail is for persons living outside of Europe. 

With Interrail you have the outbound/inbound rule saying that you can travel on a maximum of two travel days in your country of residence. 

There is no pass fare for a private compartment on a Nightjet.

These prices are not really special offers. They're always there but availability is limited and the chance to get them is higher when it's not so busy (like now).

Nightjet does not have a class distinction.

Thank you for ur answers rvdborgt.

But i think there was some misunderstanding, I just did not formulate the questions clear enough.

2. But if I would have the pass, then I would still have to pay the 199 for the private compartment or another amount? What I meant was interrail pass, If I had it , would I have to pay these 199 for private compartment or maybe another amount. You answered ...There is no pass fare for a private compartment on a Nightjet…. To be honest I do not understand ur answer.
3. I meant here special offers for the interrail passes mentioned by Hector. What are prices for these passes when they are on special offers? And how often are these passes on special?

Hm yes maybe my answer was too technical… it means there is no specific pass reservation for a private couchette compartment. You can only buy a normal ticket with reservation.

Passes are often on sale in December/around Christmas/New Year, around March and around black Friday, with a discounts of 10 or 15% or on black Friday maybe 20%. Subscribe to the Interrail newsletter to be informed when the next one starts.

Ok , I will subscribe now.

So if I had the interrail pass valid for the day of travel with the nightjet, I would still have to pay the reservation for the private compartment? 199 euro?

Hmm… I am not sure I understood it. So if I had the interrail pass valid for the day of travel with the nightjet, I would still have to pay the reservation for the private compartment? 199 euro? or not?

That is correct, for the private couchette compartment. For sleeper compartments, it works differently.

how does it work for sleeper compartments? what is the different between them?

Sleeper compartments often have 3 berths but can also be set up for 2 persons or 1 person. You will always have a private sleeper compartment if you book 3 berths in a 3-berth compartment (T3), 2 berths in a 2-berth compartment (Double) and 1 berth in a 1-berth compartment (Single). "Double” and "Single” are often just the same compartment but with a different set-up.