Flight Events - how to import a flight plan

I just start to use Flight Events map.
For some flights flight plans are displayed, for others not.

Are these only MSFS plans created before the flight, or is it also possible to import own flight plans, e.g. simbrief or littlenavmap?
If there are events, will flight plans be visible there?

Thanks and happy flying!

I’ll answer myself already.
So far nothing found in Flight Events, but what really helps me to find my friends in multiplayer mode on the Littlenavmap map seems to be the tool VirtualFlight.Online Transmitter.
I will give that a try. Virtual Flight Online Transmitter - VirtualFlight.Online