@jrbl 
Everything else regarding file parents looks okay in the code review, but I can't pull it unless prefill_children returns the jQuery.getJSON object (a jqXHR obj).  Returning this object allows the function that imports XMLs to set the exam's parent even while changing sections, by listening to the `success` event of the ajax call.  This requires a reference to the jqXHR object (the return value of the jQuery.getJSON call.)  Look at line 120 of templates/exams/renderPreview.js for details:
```
prefill_children($('#parent_id')[0]).success(prepop_children);
```
Basically, can you 
1. make sure to return the object as the code previously did
2. change the signature of the call line 120 to remove the argument `'#parent_id')[0]` as you did above
3. then test that importing xml that sets a parent in a different section still works.