Rather than passing this up to the root (which I'm not sure would be correct in all cases) I think we could follow a similar style to what we do with `_m2m_data` and `_related_data`.  If instead of returning a list we return a object that is a subclass of list but that also has a `removed_items` property that we store this extra info on.  We'll then have access to the deleted objects metadata in `.save`.