Linking a tkinter GUI objects to another script


I am new to this forum, thanks for helping in advance!
I have a basic knowledge of Python. I have made a GUI in tkinter and it has a few buttons. I would like to call (using uigetfile), select (using uigetfile), and run another python file from that GUI. I haven’t done the run part yet (because there is where I am confused about how to proceed). Running just a plain Python script using os.system(‘’) works but I want my new script to change the status of the buttons in my GUI during the execution. I don’t understand how to call the buttons of the old script (which is GUI) in the new_script. It would be great if someone could help me out here by giving me a small code segment that can help me proceed.

So, in other words, I want my old_script to call and run a new_script which would again call out callback functions of old_script to change the status of buttons during the execution. Not only that, but I also will want to pass on the device handles to the new script so that the devices talking to old_script can now talk to new_script and then pass them back to old_script after the complete execution of the new_script.

Please let me know.