The Swiss Family Card is a separate pass for children up to 15 years who travel for free. You need to order the Swiss Family Card in combination with your "adult" pass .  

Here at HappyRail that's very ease: first select your pass, add it to the card and than select the Swiss Family Card in the dropdown in the left top corner of the price table and add it to your cart. 

Quick links: 

• Swiss Travel Pass - General information
• Best seller: Swiss Travel Pass Consecutive - 4 days