Sage 300 - Apply cash receipts to detail lines in AR Invoice

SOLVED

We have a potential client and one of their requirements is to be able to apply an AR Cash receipt to invoice detail lines. So for example, if the invoice has 3 lines, maybe planning, shipping and surcharge - and the receipt covers only the shipping, they would like to be able to apply directly to the detail line.   I have not found any 3rd party products that will help with this requirement.  Any suggestions?