Joseph Hurley's November article at https://www.savingforcollege.com/article/multiple-529-accounts-for-the-same-child-does-it-ever-make-sense states that the accounts must be in different states to avoid aggregation. All accounts in the same state for the same beneficiary are aggregated for tax purposes.
Doesn't the PATH Act eliminate the aggregation requirement for distributions after December 31, 2014?