When the assets, liabilities, and membership of employee organizations sponsoring or underwriting plans approved under section 8903(3) or 8903a of this title are merged, the assets (including contingency reserves) and liabilities of the plans sponsored or underwritten by the merged organizations shall be transferred at the beginning of the contract term next following the date of the merger to the plan sponsored or underwritten by the successor organization. Each employee, annuitant, former spouse, or person having continued coverage under
section 8905a of this title affected by a merger shall be transferred to the plan sponsored or underwritten by the successor organization unless he enrolls in another plan under this chapter. If the successor organization is an organization described in
section 8901(8)(B) of this title, any employee, annuitant, former spouse, or person having continued coverage under
section 8905a of this title so transferred may not remain enrolled in the plan after the end of the contract term in which the merger occurs unless that individual is a full member of such organization (as determined under
section 8903a(d) of this title).