OData model binding read / write

Dear Experts,

For an internal training in my company I am trying to make a prototyp using Northwind OData service. As you would now you can only read data using Northwind service. I want to show examples about deleting and adding items. What would the best approach to do this? Deleting and adding should be of course only faked in the UI and not persisted. For example like in Approve Purchase Orders example. Can I clone the model and work on it? I realized that I couldn't even call oModel.setData using Northwind. I would be happy about every input and suggestions.

Thanks and Regards,

Koray