I found the answer at last.
The Settings for how many MIDI ports (each?) instance should have are visible when you click on the cog-wheel icon in the top right hand corner of the Vienna Ensemble instance connection window in Cubase. The number can be changed only by typing on the number itself - the up-down arrows to the right of the numbers don’t work, at least not in my version of Cubase Elements 8.
Hope this helps someone else someday. It was helpful to me to see the OP encountered the same issue, and solved it with a settings change in Cubase.