Windows API design

[Luckie]

I don't know what your c-programs accept for parameters and how they handle them.

But I still wonder what you mean when you say, "execute the C executable in these child windows".

As a matter of fact you have two processes: Your own and the c-program you started from within your application (process). Now tell me what do you want to do with the second process you started from within your application.

I'm afraid you try do something that can't be done or there is a better solution than yours.