I've just seen your questions on ASF Slack and didn't immediately make the connection that this post in the mailing list is one and the same. I understand what you're doing now -- you have an existing DC with no encryption and you want to add a new DC with encryption enabled but don't want the downtime associated with enabling encryption on the existing DC.
As driftx, exlt, myself & co pointed out, there isn't a "transitional path" of implementing it without downtime in the current (released) versions of C*. Cheers! >
