On a related note, I've been testing sending invoices and have another issue.  While the Invoice sent shows the line item detail of the payments, once the member clicks on "Pay Now", they are taken to the checkout page where they can enter their credit card info and the amount they will pay. But there is no comment or memo box for them to identify how their payment can be applied. 

For example, if they pay $100, I won't have a way to identify which of the optional funds should receive the extra payment. Any way for customers to enter a note on the payment in this process?

Thanks