This is more of a administrative question, and depends entirely on how you would like to administer the accounts. There are no material tax, financial aid, or return benefits from using a single or separate accounts.
As a father of triplets, I opened separate accounts for each child. For me, since they would all be in school at the same time, it seemed easier to administer the accounts separately. So far it's been a good decision.
Parents of singletons can more easily use a single account and change the beneficiary as needed.
VP, Research & Development
This information does not constitute tax advice and is provided for informational purposes only. Please consult your tax advisor, financial advisor, local taxing authority, and/or plan provider or sponsor for more information.