Is there a way to have a program in a launch file{which contains other functions} shutdown a second program within that same launch file under certain conditions, and restart that program again under other conditions? For example said launch file:

https://github.com/DistroIII/Project/blob/master/launch/ex.launch

I wish to be able to stop and restart ArnoldLogistic_coverage.py using evade.py. I have been looking up stuff like rosnode kill and ros request shutdown but I have no idea if they are useful, does anyone have any ideas? On a second look at this, this seems like a case of trying to tart and stop a node via another node. I don't know how to achive this. Please help. Or am I going about this wrong and might there be a better way to go about achieving this aim?