Hello @chaitanyap
Thank you for your question.
Normally you will receive the Swiss Family Card for your kids. During the purchase you could select that your children travel with you and they received the Swiss Family Card in order to travel free of charge.

If you don't have select that you can ask at a desk in the train station when you will arrive in Switzerland. Search here for your desired station and its opening hours.
I wish you a nice day.
Kind regards, GiorgiaB