It's unlikely you are going to get anything other than personal opinions on this.
The only type of account that I know of where a child owns the money, but is not a signatory is the UTMA. (A court appointed guardianship account would be another, but they are generally subject to public reporting; privacy isn't much of an issue.) The model UTMA statute simply doesn't say anything about whether the depository institution can provide information to the beneficiary.
In a like fashion, SSA and VA say nothing about whether the depository institution can provide information to the person to whom the benefit is payable. They do suggest the person entitled to the benefit ask the fiduciary any questions they might have about the way the money is handled.
As the ownership is clear, I personally see no basis for denying information to the actual owner of the funds. If the funds are being misused the owner would have no way of finding out other than by asking you how much is there and, perhaps, more. Moreover, a person for whom a personal representative has been appointed may be legally competent and a child for whom a UTMA is established may be over the age of 18, but the delivery age under state law is 21.