Corporations not for profit, of this class, previously organized under the general incorporation laws or laws later enacted, are empowered to combine into associations upon such terms as may be provided and agreed upon, or by one corporation becoming a member of the other. Further, preexisting charters of the corporations are amended, under the power reserved to the general assembly, so as to bring same into conformity with this law, thus granting them the powers and imposing upon them the duties and liabilities set forth in this chapter.