With a roundtrip family ticket you are able to take the gondola both ways, with 2 adults and 2 children.
When you purchase a roundtrip family ticket, you can go straight to the ticket gate.
Use the QR-code that you recevied both as an e-mail and as a message to get through the ticket gate. This QR-code is only valid once at the lower station and once at the top station, the same day.
This ticket is valid for the date you choose.