Wishlist: Linkage between payments and billings they "pay for"

Evergreen currently does not provide any linkage between payments and the billing line items that they apply to, even though from the client side, staff are able to select which billings are affected when applying a payment. This is most troublesome when creating payment reports where the expectation is to see how many, for example, lost book charges were paid this month. I don't have great ideas about implementation, but I think this would be a very useful feature to add.