You're on the right track with the Key. The Key uniquely identifies a given entry.
The other thing you need to do is model the stored attribute (wherever you're putting this) as a One to Many class, which is a checkbox in the Model Attributes dialogue. This tells the inventory server to actually make use of the key value to create many entries for one attribute when a unique value is encountered.
Ah great - Ok so i set the Name attribute to the Key and then made sure the Modelled data table was one to many - so lets see what starts to come back.
Will update soon..
Thanks man that was the key - the one to many - all sorted!