Hi Alessia, this is an issue on our side. As a workaround you will need to add the travellers in the '’trips and travellers'’ section in your account. You will be asked for a Pass Cover number. Our Customer Support team can provide you with one. If you did not reach out already, you can do so here. 

Hello, me and my group are having the same problem. I already duplicated the trip then added my friends to it, but when we try to book a reservation as a group it says “unavailable”. I’m not sure what you meant in your reply since I have already added my friends. I have also already contacted Customer Support last week but they still haven’t replied yet.

There are also other (and often cheaper) ways to book reservations. If you let us know which trains you would like to book, then people can give advice about alternative ways.

We are currently trying to book a reservation for a train from Munich to Venice on the 7th of August. Since we planned our trip for Italy, we will also be looking to book reservations for normal trains and night trains between cities in Italy.

Munich to Italy is a bit of a special case. Reservation is optional but there is a 10 EUR supplement for the Italian part of the journey. You can buy the supplement online via ÖBB or in the train (the price is the same). The optional reservation is also available via ÖBB (3 EUR).

For domestic Italian reservations, the best is to go to a ticket office, as soon as you arrive in Italy.

Thank you so much for your help! We were able to book a reservation through the ÖBB website. Can you explain what exactly the supplement is, is it different from the reservation fee? Also, the Interrail App told us that reservations are required for the train we picked (ECB 87).

The app is wrong in this case, although it is currently a good idea to have a reservation because it can be very busy in the summer. The supplement is indeed something different than the reservation. ÖBB call it "Aufpreis Brennerverkehr Passzuschlag”.

The supplement is neccessary because this is a cooperation transport and so ÖBB-DB don’t earn money on the Italian part with Interrail tickets (or at least a very low amount?), that’s why they ask for a supplement to generate at least some revenue on that part...

Have they said that? Other non-incumbent operators (e.g. LEO, RegioJet, WestBahn) seem to be able to manage without or with a more moderate fee. I'd say the 10 € supplement fits in the Italian tradition that any fast train should have a supplement. At the time Trenitalia was still operating these EC trains south of Brenner, they already required a supplement, so the current one is just a continuation of that practice.

I thought I’ve read something about this in a railway forum Often it is also cheaper to buy a Sparpreis/Sparschiene (to Brenner/Brennero for 19€) than to pay the supplement with interrail (if you use a flexi pass).
Regiojet, LEO and WestBahn are operating on a national network and will get something from the amount of the Interrail revenues which are going to Austria, CZ or whatever (I suppose). And on Regiojet Interrail is e.g. not valid on the Prague-Split train… (as they wouldn’t get any money from Croatia or Hungary for running this train). So that’s why it would make sense to get some fee for using that trains from Brennero… because from there to Munich no supplement is required.

Well nevermind, the fee is or so 10€ extra to the reservation fee as you said :)

AFAIK, whether or not they get any money depends on wat they have agreed with Eurail bv. And how the income is distributed depends on pass usage, which is why you can send in your pass cover (not sure how they do it with mobile passes though).