Emails seem to not be backed up with symlink

One question. In the machine setup section of the guide it mentions running the command below when updating.
curl -s https://mailinabox.email/setup.sh | sudo -E bash

could I just update the setup.sh STORAGE_ROOT variable to my mounted drive and run the curl command and then sudo mailinabox instead of spinning up a new DO droplet? Or changing the STORAGE_ROOT wont work with updating MiaB? Only on first install?