In El Paso, Texas, establishing paternity can be done by signing an Acknowledgment of Paternity (AOP) form, which is available at the hospital at the time of the child's birth or at the Texas Vital Statistics Unit. If the parents are not married, the father's name will not appear on the birth certificate until the AOP is signed. Other methods include obtaining a court order or conducting a DNA test. If the mother is married to someone other than the biological father, the presumed father must get a court order to establish paternity.