[Zope-dev] Mapping groups of users to local roles

Hi, I have the need to make a group extension to the permission system in Zope. I need to make so kind of folder or acl_extender that can know about groups of users and map them to local roles. As I understand the security system user get their role mapping through a UserManager (acl_users). But what I want is to have a central UserManager (possibly LoginManager or using the PTK member system), but on a branch level extend the it with user-group-role mapping. Any ideas on how to solve this problem? Maybe someone already have thought about this? I anticipate using ZPatterns to do the mapping separating the storage from the logic. Regards, Johan Carlsson