Depends on where this message is shown / or transmitted from. In the MissionEditor/GameGUI.lua are events, what you can do is execute an additional function to pass the argument to for example your Kneeboard. At the moment i'm working on a custom GameMessages system with score credit messages and hit messages. A bit similar to War Thunder game notifications.
Example of my code now:
function onGameBdaEvent(eventName,arg1,arg2,arg3,arg4,arg5,arg6,arg7)
--print("---onGameBdaEvent : isOn(): ", Bda.isOn())
--print("---onGameBdaEvent(%s)-----",eventName,arg1,arg2,arg3,arg4,arg5,arg6,arg7)
if Bda.isOn() then
Bda.startTime()
Bda.onGameBdaEvent(eventName,arg1,arg2,arg3,arg4,arg5,arg6,arg7)
end
onArcadeEvent(eventName,arg1,arg2,arg3,arg4,arg5,arg6,arg7)
end
As you can see, i use the existing event to pass it to my custom event (onArcadeEvent) with the arguments from the original. This way you don't mess with the existing logic and just only inject your own function.