It is often necessary to add lines manually to a system-generated invoice to accommodate the following business requirements:

• To invoice customers for additional costs incurred at the end of each month.
• To bill customers for miscellaneous charges based on a pre-existing contract and incurred from time to time.
• To accommodate customer requests for adjustments to the invoice amount.

The benefit of adding the manual lines is two-fold, first, you have a single invoice to cater for all the charges incurred in a particular time period and secondly, you do not have to create a quote or order line to accommodate any miscellaneous charges.