Negative Time Entries - Enabling T&M

Hi community, Looking to see if anyone has any ideas to solve an issue we're running into while setting up integrations with our accounting systems. Some of our projects are billed on time and materials (T&M), and one of our requirements for enabling this time entry in Workfront (and connecting to our accounting system) is to be able to make negative time entries. This would allow us to effectively zero-out an overcharge from the time period prior, but account for it in the current time period. Because the past time period is already billed, we do not want to go and literally zero-out that entry. Workfront's timesheets do not allow for negative time entries. We've been discussing what our workaround options might be for this, but have hit a wall, so I wanted to throw the use case to the community to see if there are any ideas from others who may have experienced similar issues. Thank you in advance for any help/ideas! Mike Clark Sr. Program Manager Healthgrades