The Council has the power and authority to by legislative act merge, consolidate or transfer to or under the applicable provisions of this Division any or all of the special taxing areas, special improvement districts services, functions, or improvements that have been established, created or provided under the existing provisions of this Code. Upon the enactment or adoption of such acts all special assessments, ad valorem taxes previously assessed or levied under the provisions of this Code are declared to be legal and after the adoption or enactment of the acts merging, consolidating or transferring the services, functions, or improvements to or under the provisions of this Division the assessments or levies shall be made under the provisions of this Division.