How to launch automation worker device

I have added some automated tests, via the IMPLEMENT_SIMPLE_AUTOMATION_TEST() macro, and also some Functional tests using the Functional Test actor. I can run these tests in Session FrontEnd and also via command line:

UE4Editor-Cmd.exe MyProject.uproject -unattended -nopause -NullRHI -Game -ExecCmds="Automation RunTests Project" -testexit="Automation Test Queue Empty"

Now I am looking at implementing functional network tests. There is one example in the engine (FMultiplayer4PlayerTest) and from what I can tell it will try and run on 2 devices.

However the test doesn’t run because there is only 1 device. I’m guessing there’s a cmd line I’m missing because I launching the game, launching the editor, etc, and I never saw a second device appear in Session Frontend!
I’m specifically talking about Windows here, and I want multiple test workers running on the same machine (or maybe another machine on the LAN if necessary).

How do I run another instance and get it to show up as a Device in the ‘Cluster’?