(a) The position held by the employee immediately before the leave is commenced shall be held upon a period not to exceed the twelve-week period of the parental leave and the employee shall be returned to that position: Provided, That the employer may employ a temporary employee or temporary employees to fill said position for the period of the parental leave.
(b) No employer may, because an employee received family leave or medical leave, reduce or deny any employment benefit or seniority which accrued to the employee before his or her leave commenced.