Migrate from Isilon Gen5 to Gen6

We had a migrated solution from 5 nodes Gen5 X200 to a new one 4 node Gen6 A200.

We a 8 port infiniband switch, and due this , we can only connect at starting 3 of the new 4 nodes.

The proposal solution is power-up the four A200 nodes and ad only 3 to the cluster using the 3 empty infiniband port. Then move data from old nodes to new one and smartfail one note in order to connect the 4º A200 to the switch, and continue then with smartfail the other old nodes.

It's posible do this, or we must add the the current cluster the 4 new nodes (Due new config requirement for Gen6 nodes) ? 

Regards