Such consolidation commission shall prepare a consolidation ordinance in which provision shall be made for the allocation of local governmental functions and services to existing offices, departments, boards, commissions or other agencies of the town, city, borough or other unit of local government; the abolition of unnecessary offices, departments, boards, commissions or other agencies; the definition of areas in which services are to be rendered; the establishment of necessary taxing districts to pay the cost of such services; the distribution of assets and liabilities, and such other matters as are required to effectuate such consolidation, including the necessary revision of the charter of any of the units of local government under consolidation so as to eliminate unnecessary offices, departments, boards, commissions or other agencies or to expand existing offices, departments, boards, commissions or other agencies and so to render such charter effective as the charter of the consolidated municipality; provided the terms of the consolidation ordinance shall not, in terms or effect, impair the contractual obligations of the town, city, borough or other unit of local government.