Tex. R. Civ. P. 279
Upon appeal all independent grounds of recovery or of defense not conclusively established under the evidence and no element of which is submitted or requested are waived. When a ground of recovery or defense consists of more than one element, if one or more of such elements necessary to sustain such ground of recovery or defense, and necessarily referable thereto, are submitted to and found by the jury, and one or more of such elements are omitted from the charge, without request or objection, and there is factually sufficient evidence to support a finding thereon, the trial court, at the request of either party, may after notice and hearing and at any time before the judgment is rendered, make and file written findings on such omitted element or elements in support of the judgment. If no such written findings are made, such omitted element or elements shall be deemed found by the court in such manner as to support the judgment. A claim that the evidence was legally or factually insufficient to warrant the submission of any question may be made for the first time after verdict, regardless of whether the submission of such question was requested by the complainant.
Tex. R. Civ. P. 279