I would organize this a little differently to get it to work with the MM base biz webform.

You're probably only registering the Security bo in the form correct? Your will need to register both the Security object and the Contact object in the webform, which means you'll need to instantiate the Contact bo in the web form. Then, in the webform, set your Security.oContact property to that instantiated Contact object.

On your controls set the binding properties in the normal way where BindingSource=Contact.