40a(3)

As per Income Tax Act , it is very clear that payment in excess of Rs.20000 made on a single day to the same person other wise by way of an account payee cheque shall be disallowed and added back to business income

In the exceptions to the section 40A (3), as per Rule 6DD there is no instance where payment in excess of Rs.20000 other wise by way of account payee cheque to a minor, the payment is an allowable expenditure.

Hence,  the said expenditure is disallowable, and it is not tenable to make payment as per your example (Read Rule 6DD for detailed explanation)