My son is four. His father has been around all his life. As of right now seen on paper he's not the father... I know he is he's the only possibility. At the time of my son's birth his father wasn't there so I gave him my last name. Now we are expecting a little girl and I want them to all have the same last name. Would I have to get another paternity test? We both believe that the last paternity test was inaccurate. What do I do at this point? We live in Ohio.

Paternity DNA tests are very reliable, almost no chance of mistake if done by a proper lab.

But if you want him added to birth certificate, you will file motion in court, get a DNA from approved lab by the court and get him added.

But if you want him added to birth certificate, you will file motion in court, get a DNA from approved lab by the court and get him added.

... or you and he may sign Acknowledgment of Paternity.