Adding custom indicator to QGC

Hello every1.

I have a question about how to add custom indicator to QGC.
I have modified px4 ardusub firmware, so it transmits custom mavlink temperature message to QGC for each sealed battery container. (my rov has 2 sealed containers). Now i’m trying to get data from this message and put it in custom indicator (similar to battery indicator). I’ve already modified mavlink message definitions in QGC xml, but what to do next?

What is the correct sequence of actions to achieve this?

Will be appreciate for any help.

ArduSub is ArduPilot firmware, not PX4, so I’d suggest asking in