Hello MJDRod
The Swiss Family Card is the childās ticket. You do not need to purchase additional tickets for the children when you have the Swiss Family Card, at least not for trips where the Swiss Family Card is accepted, and this is the case for almost all public transportation in Switzerland.
https://www.myswitzerland.com/de-ch/planung/transport-aufenthalt/billette/swiss-family-card/
The only condition: when a child travels with a Swiss Family Card, then it must be accompanied by at least 1 parent holding a valid ticket.
For all e-tickets, Swiss Half Fare Card, Swiss Family Card, etc. you need your physical (no paper copies, no images of it on smartphones) passport or government ID. An ID check during the ticket check is anytime possible.
Kind regards,
Roland