It would be smart to test failover of the disks to the other nodes before adding them to the SQL cluster. You can do that in the windows cluster without impacting the cluster. This validates the signatures in the cluster and the nodes are properly sync'ed for the new disks. Especially since there are no dependencies at this point. I have added SAN Lun's before that did not come online when moved to alternated cluster nodes, while it did come online for primary node. Thanks