A municipality employing reserve officers may adopt appropriate legislation extending the relief provisions of this chapter to its reserve officers. The relief provisions of this chapter may not be extended to reserve officers if the municipality has extended industrial insurance coverage to its reserve officers under RCW 51.12.140 or 51.12.035(2), or any other provision of law. A municipality that adopts appropriate legislation extending the relief provisions of this chapter to its reserve officers shall enjoy the same extent of immunity from civil actions for personal injuries to its reserve officers that arises if the reserve officers were covered under Title 51 RCW.