My daughter is not the biological factor of my former husband, although we were married at the time she was conceived and born and for three years after that. He continued to have visitation, paid child support, provided health insurance and claimed her on his taxes. She is now seven years old, and he has decided he doesn't have to pay for her any more. My lawyer says there is a good chance he does have to pay because he is the only father she has known -- and something about equitable estoppel. What to do?
I assume that what your lawyer meant by equitable estoppel was that your ex should not be allowed to deny that he is the father of the child after so many years of activity that indicated just the opposite. This would be based on the argument that it is fundamentally unfair to everyone to "de-father" a child.
Whether or not this type of legal argument would hold water depends on how this branch of the law has developed in your state. In some states, such as California, a husband is 100% presumed to be the father of a child born to the marriage. In other states, the husband is off the hook if he can prove the contrary. But even in those states, a judge has the ability to make fatherhood stick if the man in question has acted like a father.
Now some advice that has little to do with the law: Be careful what you ask for; you just might get it. If you force fatherhood on your ex because of your need for the child support, you may come to regret having him have that status, due to the fact that he will then have the right to come into court to raise custody and visitation issues as long as your child is a minor. Take a good hard look at whether the child support is important enough to force your ex into being a legal parent, with all that that implies. While your child appears to have an arguable right to support from your ex, this might not mean that pursuing that right is your best approach.