After both municipalities adopt the proposal of unification, the municipalities shall prepare a unified charter. Each municipality shall appoint three, four, or five representatives to serve on a charter commission. Each municipality shall appoint the same number of representatives. The representatives shall meet as a charter commission. Within 6 months after the municipalities adopt the proposal of unification, the commission shall draft a proposed unified charter. The charter commission shall elect officers from among the representatives. As the representatives consider necessary, the charter commission may adopt rules to govern meetings and expedite the drafting of the unified charter.