Positive balances to auto-apply to future fees

We charge fees per term and have a number of parents who will add payments to their accounts so that they're sitting with a positive balance before fees are applied.

These "prepayments" should be automatically applied to the fees when they're added to an account, and auto-split if needed. A lot of manual work is created and very hard to keep track of when you have a large number of students.

Should payments not just be auto-applied to the oldest line, and so on, if specific fees aren't selected?