Notwithstanding the provisions of section five of this article, the assets of two or more protected cells may be combined for purposes of investment, and such combination shall not be construed as defeating the segregation of such assets for accounting or other purposes. Sponsored captive insurance companies shall comply with the investment requirements contained in article eight of this chapter, as applicable: Provided, That compliance with such investment requirements shall be waived for sponsored captive insurance companies to the extent that credit for reinsurance ceded to reinsurers is allowed pursuant to section eleven, article thirty-one of this chapter or to the extent otherwise deemed reasonable and appropriate by the commissioner. Notwithstanding any other provision of this chapter, the commissioner may approve the use of alternative reliable methods of valuation and rating.