[Zope] Q: User acquisition with exUserFolder

Hi, I'm working on a Zope application where I need different user folders at different parts of the site. Furthermore, I need subfolder to acquire users from superfolders, which works fine with standard (HTTP) authentication, with both the standard Zope User Folder and exUserFolder. However, I use exUserFolder's Cookie based authentication, because my users are more comfortable with a login form and proper logout. When I use that, exUserFolder no longer acquires users from "upper" user folders, even other cookie based exUserFolders. Is this a bug or a feature of exUserFolder? In either case, is there a workaround? thanks in advance pA