Essentially Encoders are just buttons. The timing is weird on them, but you can chain them like a switch. As long as you have space in the software for encoders, you can add more.
Thanks SolderMonkey. So I assume from your comment that I must maintain the outer pins as individual columns as I found that when I placed middle pins as individual rows I could not get 2 encoders working correctly. I setup outer pins into 2 common columns as it suited me more to have less columns used.
However, as I did not want to use encoder push buttons I did not wire those in anywhere on assumption that they were optional. DO I need to wire them in?