(a) A district may add or exclude land in accordance with this subchapter:
(1) after a district is created by order of the commission or another governmental entity or by special Act of the legislature; and
(2) before a confirmation election is held as required by § 49.102.
(b) If land is added or excluded as provided by this section, the election to confirm the district required by § 49.102 shall be to confirm the district as modified.