I also would like to design a Model relationship so that you can only create an attribute through an Owner model. For example, a User has to create a Quote, and each Quote will be created with a connection to the User. I figure this is the easiest way to perform service encapsulation.
What is the best way to do this?
One approach I had thought of was using a controller and custom event on the 'owner' Model, to create the instance Model, and then add it to a list in the model. All of the CRUD operations for the instance model would only be accessible from the Owner.