In the transcript of the meeting 14/2553 of March 4 by board 2 of the board to consider draft laws - those transcripts where I normally only check for the municipality upgrades - it had only one topic on the agenda.
Villagers from Ban Takhian Khu (บ้านตะเคียนคู่), Mu 13 of Takhop subdistrict, Pak Thong Chai district, Nakhon Ratchasima province have complained about the bad road towards the district office, and since the one of Wang Nam Khiao is only 12 km (compared to 46 km to Pak Thong Chai) they requested to have the village attached to the TAO Wang Nam Khio.
Though the request is denied by the board, and the villages have to ask for an adjust of the district boundaries instead, the rationale for this decision is interesting. The transcript quotes the relevant Tambon Council and Tambon Administrative Organization Act of 1992, which in section 41 states that TAO with adjoining borders and in the same district can join into a single TAO. At first, this is only allowed within the same district, and also does only cover the dissolution of one TAO and joining into the neighboring TAO. Therefore this section does not say anything on a boundary change, something which seems not to be mentioned at all in this act. Yet it seems the board follows the interpretation that a TAO boundary must coincide with the subdistrict boundary - except of course there's an overlapping municipality.