How to start an external tool before *and during* my main program?

Hello

I wanted to start an external tool before launching my Python script. 

I added the tool to the 'External tool' list and configured it to start. It does start.

The problem is that the main program does not. I suspect the main program (the Python script) will be started once this external tool is done (exits). In my case it does not exit, it should be running while I run the Python script.

is there a way to inform PyCharm to

• first start the external tool
• and then start my script despite the fact that the external tool still runs?

Thank you in advance for any pointers