Data is now being submitted for the new or changed custom fields when a new or edited record is saved.

Next I need to add the code to MdhCustomFieldSet which will populate itself from the submitted data (populateFromFormData). The core issue we have is that we don't know exactly what the actual parameter name will look like; we know it'll be "cf.[parentId].[customFieldId].", but the last component could be either 0 (for a new record), or another integer (if it's a modification to an existing field). I'm not quite sure how to go about finding an item in the $_REQUEST array under these circumstances.