How QGC communicates with multivehicle through one port

I have one theoretical question. When there are several vehicles connected to QGC through one serial port, and then how can QGC guarantee the messages sent from each vehicle can’t be in disorder?
Can you give me some help to understand that?
thanks in advance.

Each vehicles message are tagged with the unique vehicle id. Just because there are multiple things writing to the same port doesn’t mean things will get out of sequence. They still come out the other end in the same sequence.

Thank you very much for your apply. Now I have understood it. By the way, can I ask you another question? That is how to display two vehicles’ trajectories in the flightmap at the same time, I have try it almost 3 weeks. Any suggestions? Thank you!

That is not supported

Alright. Thank you all the same!