IIS FTP issue

I’m running NT 4.0/spk 6 with IIS. I have one external IP address bound to the internal address of the server through NAT. This external IP address is our FTP address that is used for company A who drops files overnight into their default directory on FTProot. Can I create another directory and have company B login and automatically be dropped into their own directory? I haven’t been able to set it up where a second company can login and automatically be placed in their home folder. Is UNIX the only OS that does this for FTPing?