Hi Leonardo,
Wrap your list view or data grid in a Helper dataview that you feed from a microflow.
Make sure your Helper object is associated with the objects you want to show in the data grid.
Then instead of mx.data.get with xpath use only mx.data.get with path, or use _contextObj.fetch(path, callback)
This is the way to retrieve non-persistant entites by association.
Hope this helps,
Andrej