Thankyou for correcting my syntax error, I got the folder to be mounted to the uba1, but now I ge the following error whenever I try to access the desktop or edit files on the desktop:

Service
'/UNIONFS/usr/share/applications/kde/kwrite.desktop' is
malformatted.

Does the above error mean that I need to reformat the drive in some special way before mounting /usr to the uba1 without causing errors?