Any corporation now organized and existing under title 48, chapter 11 [repealed] as it existed prior to July 1, 1969, or any corporation now existing and operating under chapter 28 of this title, may become a corporation with the powers of a corporation newly organized under this chapter and become subject to this chapter by amending its charter so as to provide for both medical benefits and hospital services as provided by this chapter and conforming to this chapter, but shall at all times be required before the amendment becomes effective to have the amendment approved by the commissioner, as provided in §56-29-104.