Can a DLL access components from calling program?

[MoonchildHK]

I am writing a simple plugin system for one of my programs usng DLLs (Dyamically linked, using GetProcAddress), but have run into a problem:

I am passing the pointer to a TTreeView to one of the functions in the DLL, but when the DLL tried to add a node to that TreeView, it throws and exception.

Is there anyway that a DLL can manipulate components from the calling application?

Also, when I try and create new components inside the DLL, what should the owner be? I have tried 'this' which doesn't work, and I have tried passing an owner from the calling application ,which then causes the DLL to throw an exception.

Any help, or pointer to articles about this would be greatly appreciated.

Thanks