Merging unencrypted pool into encrypted pool (temporarily)

We have two RAID6 pools, one with a single unencrypted member and another with three encrypted members.  We want to get rid of the unencrypted member and pool, but it currently holds 75TB of data that needs to be moved.

My plan was going to be to merge RAID6 into RAID6-encrypted, then move the unencrypted member back to its own pool prior to deleting it.  Is this the recommended approach for what we're trying to accomplish?

Also, two of the encrypted members are new and still performing RAID verification.  Do we need to wait for that to complete before doing any merging and/or deleting?

Thanks.