>ThisForm.AddProperty("TestObject")
>ThisForm.TestObject = NewObject("Test","NewLibrary","TestApp.exe")
>When I Instantiate the New Class, via command window, the 'TestObject' is not there.

This is simply adding an object reference to a property on your form, which doesn't do much. TO actually add TeswtObject, use the addobject or newobject method of the form:

Thisform.NewObject('TestObject', 'test', 'newlibrary')
Thisform.TestObject.Visible = .T.

Notice I also havce to make it visible there.