Following the hearing or election, as the case may be, the board shall decide if the proposed division is to be formed. If the board decides to form the division, it may make changes in the boundaries as it finds proper and shall define and establish the boundaries. The changes shall not include any territory outside of the boundaries described in the petition or resolution unless the board has given at least 15 days’ notice of its intention to include that territory in the division. The notice shall be given by publication, in the the manner authorized by Section 1196, and by leaving a copy of the notice at each place of abode in the outside territory.