When you're the stepparent of a child, you're not the child's parent, and that means you won't necessarily have any right to make decisions. Fortunately, there are a few ways you can gain some rights to take actions in your stepchild's best interests.
Can stepparents make legal decisions for the benefit of a stepchild?
To be recognized legally as a parent, the stepparent must adopt the stepchild. This isn't always possible, as the other parent, whether it's the father or mother, would need to give up his or her parental rights.
Some states allow for third-parent adoptions to help prevent this from becoming an issue. They treat a third-parent adoption as a case-by-case issue. New Hampshire does not allow third-parent adoptions.
Although stepparent isn't a real parent to the child in the eyes of the law, that doesn't mean he or she can't have some say in the child's life. Parents may draft agreements in which the stepparent is given some rights. For instance, both biological parents may agree that a stepparent should be able to make decisions about the child's need for medical care or schooling if they are all in agreement on those subjects.
Many agreements allow the stepparent to make day-to-day decisions while requiring a biological parent to make more important, life-altering decisions. In most cases, unless the stepparent has adopted the child, the biological parents retain full legal custody in the case of a marriage with a stepparent ending.
If this situation is like yours, you may want to discuss your options with your spouse and attorney. If you can't adopt your stepchild, then creating a parenting plan with you included might work.
Source: FindLaw, "Can Stepparents Make Legal Decisions for a Stepchild?," George Khoury, accessed Jan. 24, 2017