From what I understand of the documentation the way import mappings work when implementing producing an object with 'find by key' operations is as follows:
1. Find the object by key using xpath
2. Set association between found objects
It would be convenient if the 'Find by key' operations for child objects also considered parent associations in their xpaths.
So, it would look more like this:
1. Find parent object by key using xpath
2. Cascade down to child objects and find them by key also considering parent associations from found object in step 1
3. If no object is found create a new object and set association to parent object from step 1
It may be best to set this feature to a toggle per child entity if at all possible