CreateThread... maybe

If I've opened a new process of Internet Explorer using the Shell command, it returns to me the process ID of that process of IEXPLORE.EXE, right? Ok, so my question is, I want to open a new Internet Explorer window, but I don't want to start a new process, I want to basically open a child window. How do I do this?

I've tried using the SendMessage API and sending WM_CREATE, but this just makes a new IE window in a separate process, so it's not a child window. Would CreateThread work? Or is there a CreateChild Message? Something better?

Also, when I get the returned ProcessID from the Shell command, how can I get the window handle? What I did when I used the SendMessage API was I just sent the ProcessID instead of the WindowHandle, is that a bad thing?

Any help would be greatly appreciated, for I just need to know how to open a child window of IE under a specified ProcessID of IE.

Thank you,

Jacob