Dynamic FTP root (user isolation)

I am looking into the possibility of moving our FTP server from a Windows 2012 VM to our ReadyNAS device, but I'm hitting a sticking point with user isolation. In our current Windows based setup, we have a share called 'FTP', with sub-folders for our various customers. We've set up the server so that when they connect, their placed directly into their subfolder as the root, so they cannot browse any higher and are only able to see their files.

On the ReadyNAS I cannot seem to find a way to re-create that. The best I have been able to do is lock down the other folders with permissions, so they can see everything but only open their own folders. However, we don't want them to even be able to see the other folder names for confidentaility reasons.

Is it possible to do this? The only thing close I found while searching is this post, but that seems to only let you set the root of ALL ftp connections to the same folder instead of dynamically based on user name.