Hello Krit
I wish to clarify a few things:
Each adult needs their own Swiss Half Fare Card. One card cannot be shared among multiple people.
The Half Fare Card, and the Swiss Half Fare Card have the same range of validity. Simply, the former is for residents, the latter for tourists. Whenever you read Half Fare Card, this includes the Swiss Half Fare Card.
To obtain the Swiss Family Card, please see a travel center in Switzerland. You could have ordered it together with the Swiss Half Fare Card. If you missed that step, you can only get it from the travel center as paper ticket.
Children only travel for free provided they have the Swiss Half Fare Card, and they are accompanied by at least one parent; otherwise children 6 to 15.99 years of age need a half fare ticket.
Kind regards,
Roland