What is the procedure for seeking permanent legal custody or guardianship of children in Texas

grandmother's legal custody of grandchildren: my mother and i have had temp custody of my niece and nephew for two and half years but we have actually had them longer. their parents have yet to show any improvements or effort to get the children back. we keep on having issues with the parents and we just finally want to get legal custody. we need help on finding out how. - Is this your question? Add additional information