CageFS has a mechanism to make any additional location with users content available from inside. This is a quite useful way to share needed backup directories for users if you are giving ftp/ssh access to them. Also you can use this feature to provide access to /homeabc/username when /home/username is a symlink to it.
To enable this feature the following line should be added to /etc/cagefs/cagefs.mp file:
%/homeabc
Then remount all with:
cagefsctl --remount-all
After that a user can see both his /home/username and /homeabc/username from CageFS inside. Other directories in /homeabc as well as in /home will be still hidden for him.
