Arrears Re-Order

Has anyone reversed the order that payment arrears deductions are taken?  Currently, if an employee has multiple common deductions (i.e. 4 health deductions because they were on LOA), the application takes the newest one first.  Because we are a monthly payroll  this often crosses years and as a result, different premium amounts, our users want the oldest dated arrears to come out first.  Just wondering what sort of level of effort this may be?  Thanks - Stephanie