>Tim,
>
>No, it is a WPF app, but a module that is displayed in the UI. The UI is a seperate project.. So , basically, I am designing controls , that act as views for my business objects. They are seperate projects from the main UI. They get registered with the main UI at runtime. I am following the Composite Application Guidelines (CAG) from the patterns and practices group. I have my main form integrated with CAG and MM. Now, I need to be able to do things like this.RegPrimaryBusinessObject with a user control.
>
>Does that make sense?

Well sorta. It sounds a bit tricky to tackle via messages since you don't have a straight on MM situation. There are mmUserControls that allow you access to the main form and therefore the Register Business Object methods. I am not sure if that is helpful in your case but you can check it out and maybe there is something that will lead you in the "Oh... yea" direction as far as how OakLeaf approached it in their userControls. It was in: "Creating Web Forms Applications | Working with User Controls"
Tim