Thank you Thomas for pointing me in the right direction. I'm set up for recording now and fully synced to the Arturia. Good to go 
I did follow to find the p.126 part of the manual when trying my earlier efforts to set up the connections but assumed it was specific to the new Multi-IO expander. And on seeing the path taking me into darkly vaults of the Mapping settings in Nerdseq, I thought: Cripes!
Fortunately, it was very easy to configure using the new(??) 'Learn' function in the 'MIDI Settings'. Quick visit to the 'Track Settings' for the MIDI channel, and I was done. 
Thanks again.
I did follow to find the p.126 part of the manual when trying my earlier efforts to set up the connections but assumed it was specific to the new Multi-IO expander. And on seeing the path taking me into darkly vaults of the Mapping settings in Nerdseq, I thought: Cripes!
Fortunately, it was very easy to configure using the new(??) 'Learn' function in the 'MIDI Settings'. Quick visit to the 'Track Settings' for the MIDI channel, and I was done. Thanks again.