If it shall be shown that there is any land not within the proposed district that will be affected by the construction of the proposed levee or drain, the boundary of the district shall be so changed as to include such land, and such additional landowners shall be made parties plaintiff or defendant, respectively, and summons shall be issued accordingly, as hereinbefore provided. And, upon petition of any party so summoned, filed within ten days after such summons has been served upon him, the court shall hear and decide any objection made by the petitioner as to the establishment of the district or the inclusion of the petitioner’s land in the same. After such changes in the boundary are made, the sufficiency of the petition shall be verified to determine whether or not it conforms to the requirements of § 21-295. Any person, whose lands are affected, may, at this stage of the proceedings, sign the petition so as to render same sufficient.