I want to make sure I understand what you're trying to do.
- You are the account owner of your 529 plan
- The account currently lists your niece
- You want to change the beneficiary to your nephew on your wife's side
If they're not first cousins, and I assume they're probably cousins-in-law based based on your question, then yes, you can still change the beneficiary - assuming it is allowed by your plan - until you've made your way across the family tree to the right person. Touch base with your plan provider to make sure you're filing the appropriate paperwork and there are no plan-specific restrictions. Otherwise you've got it correct to change to you, then your wife, then her nephew, assuming you're not related.
I think the family tree part is more confusing than 529 rules, honestly!
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.