Matching payments to multiple invoices can be done in the same way in both the bank and the cash register. The following steps demonstrate the process using the bank:
go to the Money – Bank menu,
above the list of records, click the Services button, specifically the Manual payment matching action,
a dialog window will open — check all the documents (invoices) you want to settle (match with the payment),
click the Finish button,
a checkmark will appear in the Matched column for the given record