Adding a new volume to Gen 3 without starting over

I formatted my Drobo Gen 3 with 4 2TB volumes. I wanted to add another one because I increased capacity. But I was trying to avoid reformatting and wiping out all the data.

What I did was create a time machine back up. This, of course did not appear on the desktop.
I then went to the disk utility and erased the this new volume, gave it a new name and reformatted as Mac OS Extended Journaled.

The volume now appears on the desktop and I can copy the data as always.
Any thoughts on this?