Milestone Billing - Adjustments

Summary:

We generate invoices using the milestone-based billing method. It appears that once a milestone-based invoice has been interfaced to AR and accepted, we are unable to update the existing milestone amount in the contract/Project Plan or modify the corresponding billing event to process an adjustment.

The options we currently see are either to create a manual billing event for the adjustment amount, or to create a new milestone in the contract, reprocess the billing, and place the existing billing event on hold.

For example, if we need to correct both the milestone date and amount for an invoice that has already been transferred to AR, what is the recommended approach or standard process for making these corrections?