adding a new volume

When doing a new setup with Drobo 3, I had a pair of 2 Tb drives and the dashboard seemed determined to make one volume at max (16 Tb). I would like to either divide that volume in 2 or add another volume with a new name and drive letter. The dashboard doesn’t seem to have any tools to do the simplest of tasks. It doesn’t even allow me to change drive letters. Where do I go from here?