Approved Leave During Vacation Period. Where an employee qualifies for sick leave, bereavement, or any other approved leave during his/her period of vacation, there shall be no deduction from vacation credits for such absence. The period of vacation so displaced shall either be added to the vacation period or reinstated for use at a later date, at the employee's option provided that it does not affect another employee's scheduled vacation. Sick leave taken under this Article must be certified by a Medical Practitioner.