When a new user is added (using adduser) the files need to be copied to each of the other hosts. A simple way is to tar up the files, copy them to a NFS mounted are (e.g., a trusted user's home directory), log in as root on the other host, cp the tar file to /tmp so that root can access it (root access to the NFS mounted home directories is not permitted) and then untar it in /etc.
This is okay for a small network! It also relies on /home being mounted by NFS from the master (altrop). Still, I need a better solution.