How to know if joystick is in command

I’m running Copter 4.0

RC setup: RFD900 TXMod RC Transmitter

Joystick setup: RC transmitter <–USB–> Mission Planner with Joystick enabled <–LTE + Mavproxy out UDP–> Raspberry Pi on UAV <–serial connection + Mavproxy–> Cube Flight Controller

This setup works most of the time.

Whenever my LTE connection is interrupted, ArduCopter returns control to my RFD900 TXMod RC Transmitter. Of course this is desired! However, as soon as the LTE connection is back up, control is returned to my Joystick RC Transmitter.

As far as I know, my only way of knowing which RC transmitter is in control is trying both.

Is there any way of knowing or setting up an alert or trigger whenever Joystick control falls back to the RC control or viceversa?

Thanks in advance!

Alvaro Sosa