(1) Unless otherwise provided in the partnership agreement, approval of a plan of merger by a domestic partnership party to the merger shall occur when the plan is approved by all of the partners.
(2) If a domestic limited partnership is a party to the merger, the plan of merger shall be adopted and approved as provided in RCW 25.10.781.
(3) If a domestic limited liability company is a party to the merger, the plan of merger shall be adopted and approved as provided in RCW 25.15.421.
(4) If a domestic corporation is a party to the merger, the plan of merger shall be adopted and approved as provided in *chapter 23B.11 RCW.