Tex. Nat. Res. Code § 51.081

A person who claims title through a source other than by personal transfer to a definite portion of a survey that is less than the whole survey purchased from the state, with the approval of the commissioner, may have the portion of land that he claims separated from the other portion of the survey on the records of the land office by filing in the land office evidence of claims that may be required by the commissioner and by paying the fees provided by law for papers filed as evidence of the claim or a right to a separation of the area.