When you book reservations for multiple people., then the reservation system tries to find seats near each other.

If you tell us which trains you would like to book, people here can suggest websites or ways to do that. On the websites of some railway companies, you can choose the seats yourself.

We had already booked most of our trains, but we gonna ask people if they can let us seat together, the last train that we have to book it’s roma napoli, do you know how we can do to seat near each other on that train ? 

Book that one in Italy, at the Trenitalia ticket office, as soon as you are in Italy. If it's a few days in advance, that shouldn't be a problem.

Hello,  I am travelling as a family and had added everyone onto my account.  However when I tried to reserve a seat it only allows me to reserve for one traveller.  How do I reserve for the rest of my family there is 4 of us.

Please specify route, date and departure time.

All sorted … internet took a while to update my details.  I am able to reserve tickets for all of us.