Mileage Tracker - Update process when employees change rollups

While working on incidents, we have had several situations where submitters are unable to add employees to the employee table. We detected the reason this was the case is because the employee is already in the table but under an old rollup. we'd like to have a process that would possibly present a message to the User to indicate why the user cannot be added, do a refresh where the system can detect when the rollup has changed