From the way that you are phrasing your questions, I infer that you are using the object-oriented paradigm to create "data stores" by just inventing a new object(class) when you see a need to store some more data.
Whilst I know that this approach is very popular and widely used, I think that it is a poor and ineffective way to create data structures. For example the approach leads to data duplication and lots of confusion.(such as that which you seem to be experiencing right now).
The approach that we recommend is to begin by deciding what data you need and then to design user interface code such as a web page to maintain the data. The procedure is defined in the Conceptual Schema Design Procedure (CSDP) that is described in some of the papers in the library. (For example this one: http://www.ormfoundation.org/files/folders/orm_overview/entry73.aspx)
With our fact-based approach you begin by defining facts and storing them in an object-role model. This defines your universe of discourse.
An object-role model is a semantic model. It is not related to the popular "Object-Oriented" methods which are about creating coding artefacts (objects).
If you want to look at some examples, I suggest that you download the examples stored in Library>Open Source models.