(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 Section 49.102.
(b) If land is added or excluded as provided by this section, the election to confirm the district required by Section 49.102 shall be to confirm the district as modified.