The admin wants to create virtual user accounts for michelle, danielle, and cheryl. The admin creates the directories /home/ftponly/michelle, /home/ftponly/danielle, and /home/ftponly/cheryl. All directories are owned by the ftponly account.
Next, the admin creates a NcFTPd Password Database containing the virtual user accounts for michelle, danielle, and cheryl. The virtual users are created so that they all use the UID and GID for the ftponly user and group.
Finally, the admin verifies that the general.cf has the u-always-restrict-virtual-users option set to yes. This allows the site to share the same ftponly UID and GID for all the virtual users, because one virtual user only has access to the directory they login in as, since the virtual user is restricted to their directory. Since the ftponly user cannot really login, there is no risk that the contents of the various virtual accounts can be modified.