Ind. Code § 20-25-5-17

Sec. 17. Notwithstanding any other statute that provides that the boundaries of a school city or school town are coterminous or coextensive with the boundaries of a civil city or civil town, the boundaries of a school city may be changed after March 8, 1961, solely by annexation under this chapter if this chapter was in effect at the time the annexation became effective or finally effective.