C# redirecting data to an already running console exe

What I want todo:

I want to start a built console application (AppB) from within another console application (AppA). AppA starts AppB without any arguments. All AppB does is to go into its Main() Method and call Console.ReadLine().

Now I want that AppA sends a string of data over to AppB's Console.ReadLine(). Is this even possibel? (I know I can send streams to a new Console.exe but that's not what I need.)