Not sure if I understand your question. In ProcesManager you can kill (stop) processes. Are these sub-processes (processes that apparently originate from the mother process) called threads? They can be stopped as well.
Have you got a thread running that won't stop, but you can't afford to kill the parent process? Otherwise you should be programmtically killing your thread.
Under Linux each thread shows up in the process table as a separate entry, so you should be able to kill it, provided the parent process handles the thread dying and doesn't decide to exit, but that's a matter of coding.
Basically, to learn Unix you learn to understand and apply a small set of key ideas and achieve expertise by expanding both the set of ideas and your ability to apply them - Paul Murphy