I would just put the 529 account for that kid. That is what has been specifically saved for him.
Interesting that you are asked that in the scholarship section. I don't recall any questions like that when my daughter was completing the scholarship part of her applications (admittedly a while back as she is a junior

this year). Her major merit scholarship at her school was awarded without regard to need (before we even filed FAFSA). But they do have some scholarships that are both need and merit so maybe that is why they are asking?