Why not just put it in a UTMA? If parents are concerned about financial aid they could covert the UTMA to a custodial 529. Maybe the hs kid wants to backpack in Europe for a summer or do a service trip or needs a car and the UTMA would be better for them.
Should You Convert an UGMA or UTMA to a 529 plan or not? https://promocodius.com/
You set up an UGMA UTMA account for a child or grandchild several years ago. Learn why you might want to convert it to a 529 plan.If you don’t want the money in account 529 to count towards your college financial aid assessment, you can deposit the money into a UTMA account and then transfer the account to your child. However, you must make sure that your lawyer gives you accurate advice on this matter.