529 "held in names of children under age 19"

Enter the total amount parents hold in Section 529 pre-paid tuition or college savings plans or Coverdell education savings accounts established for all children, as of today. Do not include funds in custodial accounts or other savings and investment accounts held in the names of children who are under age 19 and not enrolled in college. Do not include 529 plan funds that are part of, or were funded by, a UGMA or UTMA account.

This question is from some extra USC form I’ve been asked to fill out. I’m confused. I have 3 children, 2 are “under 19 and not enrolled in college”. Parents “own” the 529s, children are “beneficiaries”. Should I only be listing the money I have for my oldest kid (age 20)? Note it is the 17 year old who is looking at USC!

No; it’s asking you to report the balances of all 529 accounts owned by a parent, regardless of who the named beneficiary is.

That is what I assumed; I just found this wording tremendously confusing.
I guess there is some deeper meaning to the “custodial” account part.

A custodial account is typically an account where a minor is the legal owner of the funds, but it is managed by a custodian (adult) until the child reaches the age of majority and can assume control. 529 accounts can be custodial accounts; for instance, when UGMA/UTMA funds are used to open a 529. Unlike a parent-owned 529 account, the beneficiary cannot be changed. Because of these factors, it should be evident why a custodial account is not reported as a parent asset on a sibling’s FAFSA or Profile.