I would add a few steps at the end. Step-6, shut off all connections on the switch side coming from the secondary of the old cluster.
Step-7, swing all cables on the primary of the old cluster to the intended primary of the new cluster & keep fingers crossed.
Step-8, troubleshoot if something doesn't come backup.
Step-9(a), if successful, swing all cables on the secondary of the old cluster to the intended secondary of the new cluster.
Step-9(b), in the worst case if you can't figure out problems in Step-8, you can either swapback all cables from the new primary to the old primary, or unshut those connections from the old secondary after shutting down the connections from the new primary and flip a-p of the old cluster.
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