I think you are confusing two different things.
First explain your setup, then maybe we can help you.
- The Tx sends data to the receiver and the receiver pass the data to FC via S-Bus or PWN connection to the FC.
- You have a Telemetry radio connected to your FC and one connected to your laptop. This is what Mavlink is using to send Telemetry data to GC software such as Mission planner.
- You want to see telemetry data inside FrSky radio LCD screen bi directionally?
For that, you need Yaapu device, lua script running on FrSky, and FrSky RX supporting that such as X-8R Rx.
or I am not understanding your question at all…