Why is #field_parents empty in nested, multi-step form? I'm using Webform, Fieldgroup and Multistep with D7.

Ultimately I'd like to create a hierarchically-grouped list of all the submitted values and display on the last step of the multi-step form, with the following format:


Page 1

Question 1 Label

Question 1 Response

Question 2 Label

Question 2 Response

Question 3 Label

Question 3 Response


Page 2

Question 4 Label

Question 4 Response

Question 5 Label

Question 5 Response

Question 6 Label

Question 6 Response




When I inspect the $form object, however, I see the fields each listed, but $form['field_my_question']['und'][0]['#field_parents'] is an empty array. 

How can I identify from the $form object which fields belong on which page of my multistep form?
I don't know what exactly #field_parents is for, but the information about field grouping is in $form (which, it turns out, is an array, not an object) several times over, in $form['#groups'], $form['#fieldgroups'], and $form['#group-children'].