You may change your child's name if it is done so for non fraudulent reasons and you have sole legal custody. The more important questions though are: 1. Is it still a good idea? 2. How is the father going to feel, not just now, but in the future? 3. How would you feel if the shoe were on the other foot? If you can honestly answer these questions and think it is still a good idea, then go ahead. But more likely than not, you are angry at your ex and this is a good way to...