The ProFTPd documentation gives good examples of how to use the DefaultRoot directive to chroot users to a specific directory.
A customer today wanted to have different chroot directories for different groups of users. The documentation didn’t mention if it was okay to include multiple DefaultRoot lines. After some experimenting, I can verify that it is allowed and works well.
I used something like this in /etc/proftpd/proftpd.conf
DefaultRoot ~ jailed DefaultRoot ~/../.. othergroup
Users in the group ‘jailed’ are chrooted to their own home directory immediately upon logging in. Users in the ‘othergroup’ are chrooted two levels up from their home directory. If you want to get really specific, each user generally has a group of their own, so you can effectively do this a the user-level as well.