Add FTP accounts with access to primary users torrent data

Hi all, another question for you:

I’d like to add some additional FTP accounts. I don’t need (nor really want) additional seedbox users, I’d just like unique FTP (SFTP) accounts for friends to log in with, and be able to download items I have in my torrent folder.

Is that something easy? Does it need to be done by hand (I did it like that on a previous seedbox script).
I assume if I add another seedbox user, that they will be locked into just what they download, where I’d want them to just access my downloads.

Thanks!!

Also would like to know this, particularly to save some LFTP scripts which has my sudoer’s password right now. I’d prefer it to have a disposable user’s password with access to FTP files