I've commented on the other thread. I think you are missing a fundamental issue with your system. Inter-process communication (IPC) between two running applications involves far more than using the same DLL. Microsoft has been working on this problem for decades.
http://msdn.microsoft.com/en-us/library/aa365574%28VS.85%29.aspxDDE was one of their first solutions.
AppB is acting like a server and AppB the client.
If the C++ DLL and AppB were not designed for inter-process communication it won't work.
