Using an Eurail Pass, you are not required to book tickets. You simply activate your pass before boarding an SBB train, and the Eurail Pass is then your ticket. It allows travels on the SBB rail network (and some others) at will.
As I said in this post, you should carefully consider your choice and ask yourself whether Eurail is the right pass for you at all: https://community.sbb.ch/t5/Swiss-Travel-Pass-travelcards/I-have-Eurail-Pass/m-p/62741#M7471
The Swiss Travel Pass or Swiss Half Fare Card might be the better offer. And they come with the complimentary Swiss Family Card, with it, children aged 6-15.99 travel for free when accompanied by one parent holding a valid ticket.
Swiss Travel Pass – the All-in-one-Ticket for Switzerland | SBB
The Half Fare Travelcard on the SwissPass | SBB
By the way, there is an excellent website from a well-experienced train traveller, The man in Seat 61. He explains the various passes available for Switzerland and might help you in making the decision for the right pass: Train travel in Switzerland | Swiss Travel Passes explained (seat61.com)