How to use more than 16 TB on ReadyNAS Pro Business Edition

I haven't been to this forum in a while and it's changed. Not sure if I'm posting in the right area, so please excuse me and let me know where to post if this is not the right place. Thanks.

I've been using my ReadyNAS Pro Business Ed. (RNDP6310) for several years and data usage has grown to the point that I wanted to upgrade the disks to 6 TB disks. I began that process and ran into an "expansion failed" log entry. I read up on it and now know expansion beyond 16 TB cannot be done. Capacities over 16 TB can only be implemented by factory resetting the device with the 6 TB drives in place.

Now to my question. I've created and run a backup job which backed the ReadyNAS to an external 8 TB MyBook drive. In the job I selected "volume c" to backup because I wanted the entire contents, not just one share. Now I want to factory reset the device and restore the data from the MyBook external drive to the ReadyNAS, and I want to be sure how to do it before I factory reset.

Question 1: Did I backup the right location from the ReadyNAS to the external MyBook? Should I have backed up individual shares instead?

Question 2: After I factory default the ReadyNAS Pro, can I just create a job to restore 'volume c' back to the root of the ReadyNAS Pro? How do I do the restore properly?

TIA,

David