[Zope] Navigation/object relationships

I am working on building a site that contains automatically-generated navigation trees and site maps. Currently, I am using a convoluted system involving properties containing a "navigation level", and am running into problems with that system as I try to extend it to handle more deeply nested parts of the site. What I am looking for is a relatively painless way to determine for an object y, contained somewhere under object x, what is the relationship/containment hierarchy from x to y? Or, at the very least, how do I obtain a given object's container? I have figured out how to do that with path expressions in TAL, but something I can do from a PythonScript would be most useful. Thanks in advance, Mike