Im building an object heirarchy in which I want to define one-to-one 'has-a' relationships which allow for both properties AND objects. For example, a Story object 'has-a' heading, body and photo. In this case, the heading and body would be text based properties, but the photo is an object. I guess what I am trying to do is promote some kinds of objects to the level of properties in zClasses. I can modify the zClass to add sub-objects at instantiation time, but this doesnt provide guarantees that the added objects wont be renamed or deleted, and the modification of the zClass add_form needs to be done at the dtml level, rather than the property sheets forms based level I am looking for. Does anyone have any Ideas as to how to approach this?