Is there any way of getting the parent from the child nsArraycontroller?

Question

using cocoa bindings, i have bound to the following:

ChildArrayController

ContentSet
bindto: ParentArrayController
controllerkey: selection
modelkeypath: children

Is there any way of getting the parent from the child controller?

[childArrayController arrangedObjects] is the children.

[childArrayController selectedObjects] is the selected children.

[childArrayController content] is an array

[childArrayController selection] is a proxy for the selected child.

I want to do something like id parent = [childArrayController xxx];