So you want to add functionality to programs you wrote, that never intended to have them, and don't want to change those programs to add it?
That kind of narrows things down, and was probably worth mentioning in our original post.
You might be able to use VI server calls from your new central app to connect to the other VI's and try to read control values. I don't know how difficult that would be.
I'd recommend changing your existing programs to add the functionality.