If you could share some details (Route ,Trains) we can suggest few pages as it´s actual a bit hard to do it via Interrail itself as they have a small problem with their system :) 

Hey,

But I created one Master trip and then I duplicated it to add my friends but I can't make a common reservation. 

We leave from France and we will go to Germany then to Prague, Vienna and Budapest ;)

Thank’s

Hi, currently there is an issue on our side regarding reservations for more than 1 traveller.

As a temporary workaround you can follow the following instructions: 

- Send a private message with your order number
- You will receive one Pass Cover number (This number can be used for all travellers)
- Go to your account -> Trips & Traveller management, add and/or edit your fellow travellers and add all missing data (the pass validity, country (for One Country Pass), start date and pass cover number.

 

Some other suggestions:

• For the TGV from Paris, go to the SNCF ticket office or call them:
  https://www.sncf.com/fr/service-client/nous-contacter/telephone
• For the ICE to Berlin, use the Deutsche Bahn website; use the "Seat only (no ticket)” option.

In both cases, you avoid the extra fee of 2 EUR per person and train that you pay when booking through Interrail. For Berlin to Prague, you can also use the Deutsche Bahn or Czech Railways.

For Prague to Vienna, you can use Czech railways or ÖBB.