Usually most railways try to seat 2 RES asked for same time as close together as can offer. So: again-in case you also did not prepare enough and read on: NOT use app for that, but directly via railway concerned. THis may give probs if it is a ´global price´ train =that they cannot sell without RES same time as ticket.

Which country are you travelling in?
Usually no problem unless they have global price tickets.

Hi, thanks for the replies :D

We are traveling together from Paris → Nice, and Barcelona → Madrid

That could be a bit tricky as these are global price tickets… (means ticket is sold only together with reservation except if you buy an interrail reservation)
Probably best to ask someone to switch seats when you are on the train. 

There are several ways to make reservations for French trains. As long as you call and make the booking they should be able to reserve 2 seats next to each other where one only is a reservation with a Eurail pass and the other is a normal ticket including a seat reservation. 

You can call  b-europe and make the reservation.

The phone call is rather expensive.

https://www.b-europe.com/EN/Contact/Contact-Centre

Another way to make reservations for French trains is to call SNCF. SNCF does not accept all credit cards though. AmEx is ok.

https://www.sncf.com/en/customer-service/contact-us/telephone

Press #85 for English, no booking fees, reservations are sent via e-mail

For domestic French reservations, you can also call NS. Also no booking fees and they do accept VISA. Remember the country code (+31)

Hi there!

I tried calling SNCF - I tried twice and both times I am put on hold for about 30mins before a recording in French plays and I am hung up on :(

My phone won’t allow me to call the b-europe number from Australia.

I tried contacting customer service for Eurail, and tried their suggestions of booking through b-europe and SNCF-connect online, but it does not work to book one traveler with a Eurail and one without :(

Any other suggestions are welcome … otherwise we might just book tickets separately and try to change seats when we get to Paris.
 

Hi @Caitlin Macnamara 

Unfortunately this is not possible through our Portal of reservations. I would suggest booking seat reservations directly with the railway company at the train station. Otherwise as suggested above by other members, you can ask to change seats with someone. 

Have a lovely day!