There are a couple more software programs involved: serial port emulators. I use 'com0com' 64 bit on the dependent computers:

and N8VBvCom on the old 32 bit main computer:

The Main Computer's VVP:

and the Main Computer's VVP Settings:

The Dependent Computer's VVP:

and the Dependent Computer's VVP Settings:

In essence it isn't a trivial exercise to get everything set up properly so it works. But it's well worth the effort.
(And as you can see my setup is very much 'over-the-top' with the backup computers and all.)