I am the custodial parent of my 7 year old son. I have been married for the past 3 yearsto a woman who is not his biological mother. My sons mother has had absolutely no contact with him for the past 5 years. My wife has been his only mother for the past 4 years. My sons biological mother does pay child support because they take it out of her check. I have no idea of where she is or how to contact her. I know that if a parent does not pay child support for a year, that would mean child abandonment. I also learned that in some states, child abandonment also means if the non-custodial parent has had no contact with the child for over a year. Could someone tell me which states those are? That way I can move to that state, establish residency, and follow through with a stepparent adoption. My wife and I would like her to adopt my son, so in case anything happens to me she would continue raising him.

Forget it. Child abandonment or not, its not going to allow for an involuntary TPR. Courts are VERY reluctant to grant a TPR and while clearing the way for adoption is a primary reason, they will not terminate a parent's rights involuntarily.

What I would do is send a letter to your ex through the support collection agency. Explain to your ex that your new wife would like to adopt your child and, that would end her support payments. If she cares so little about the child as you say, then she would probably jump at this chance.