How to 'pay' released retainage invoices in AR?

In contract billing, when retainage is released the amount of the retainage release shows as a positive invoice amount with Pay Status 'A' and a negative amount Pay Status 'R'. When you look in AR at that job the total of the Pay Status 'R' invoices should be zero. What is the normal procedure followed to 'pay' these invoices so they no longer show as outstanding? Right now our AR group waits until the release invoice is paid by the client the then includes all of the invoices in the payment but it can take several months sometimes to receive payment and it gets messy if there are many billing lines on the contract to know exactly what is owed.