如何暂停最上面的进程?(解决方案最好在c#中)

I have application written as a module on top of host app. Let's call host app process A and my app process B. Process B is in child relation to process A. From process B I start another process, called it C and while process C is running I want A and B to be suspended. To start C from B I use Process class and I block B calling WaitForExit(). But how to also block A. Again, while C is running A and B should be suspended.I have application written as a module on top o