One user, many folders

We're trying to set up where the same user (based on username) can have different directories based on different passwords. I'm running into an issue where if a user logs in, the directory he gets first is locked into the system and cannot change. So that if I log in again with the same user and a new password tied to another directory, I still get the first directory. Is there any way to unlock this and re-add the user with a new directory? Right now, just calling SftpSshServer.Users.Remove() and SftpSshServer.Users.Add() doesn't do the trick, as it keeps the older directory