PARENTAL AND/OR ADOPTIVE LEAVE. Parental/adoptive leave may be granted for a period not to exceed two (2) years. (In the case of adoptive leave, the adopted child must be less than five (5) years of age at the time of custody to be eligible for leave.) Upon completion of the leave, re-employment shall be subject to an available position, however, the employee shall have preference for re-employment for any position for which he/she is qualified that is or becomes vacant, but shall not be guaranteed the return to his/her former position.