I've been trying to set up sharing on an Unassigned Disk Device and CoPilot says that there should be a share toggle next to the listing. I've mounted three new USB connected drives and I eventually want to combine them into one volume, but CoPilot says that I must first set them to 'Share'. I clicked on the gear icon and set it to Share, but I cannot see the drives remotely or in the SMB Shares.

You can go directly to the correct support thread for that plugin by clicking its Support link on the Plugins page of your Unraid webUI.

10 hours ago, dcruff said:

I've mounted three new USB connected drives and I eventually want to combine them into one volume, but CoPilot says that I must first set them to 'Share'.

If you are going to combine the Unassigned drives into a single volume this would need to be done before any attempt to share them. Have never tried anything like this myself so cannot give any more detailed advice.

Not at all clear, however, why the drives do not show up remotely if you have mounted them and set the Share option for them at the UD level. If you attach your system’s diagnostics zip file to a new post in this thread we might be able to give feedback on that.

Thank you for your response.
What I was missing was that I needed to shut down the array first. For me, that required that I do it in the morning because I have at least a dozen streams coming off of my media server (friends and family) every day, but mostly in the evening. I also had to choose the correct file system for the 3 drives (btrfs). XFS won't work if you want to combine them into one volume.
Microsoft CoPilot was very helpful in this endeavor with step by step instructions and explanations. You have to be careful with AI because it will often lead you down the wrong path, which CoPilot did initially. Once I got on the correct path, the step by step guide from CoPilot was wonderful.
I originally wanted to go with a RAID 0 on my DAS, but was convinced by another user on this forum, as well as CoPilot, that speed should not be my concern for a backup process. Rarely, will I be backing up the entire 33TB - generally doing differential backups. And with RAID 0, my files would be striped across three drives, and if one drive fails, the entire backup is useless. Now, the files are intact on separate drives even though they are configured as one.
I have a single volume of 42TB that is running in an inexpensive DAS (Terramaster D4-320), running off USB 3.2 C connection.
Everything is working wonderfully. It took almost 2 days to back up everything using luckyBackup, but I now have peace of mind. I'm going to now schedule regular updates to the backup.
And I have very little downtime (minutes) when stopping the array.
It was a good learning experience.