Generally speaking, you don't - because one console doesn't share well with three apps: the inputs and outputs would get mixed up and it just wouldn't work.
However, it is pretty simple to create a "master app" that causes the other three to open.
Create a new app, and use
Process.Start[
^] to execute the other three, then close the "master app". If you add references to the other three projects, then the executables will be copied to the EXE folder from your master app so they are easy to find.