Additional Assignment Info page

Hi,

On our Additional Assignment Info page we have section called "Mileage Scheme". We record what mileage scheme employees are attached to. One fields was set up as unique. We have instances where employees are attached to the same Scheme more than once (with other details different like date, car reg number etc). When we try to update employee's record with the same Scheme but from different date etc the system won't allow us to do this because the Scheme field is unique. I know one of the options to fix this is to disable current field and set up