I have more than one client in a blended family. Sometimes, the family is so well blended that the stepparent considers the stepchild to be his or her actual child, but in law, they are treated differently.
If you die without a will, your stepchildren have no right of inheritance. As a result, you could end up with your estate going to one child at the expense of another, even if you intended it to be shared equally.
If you consider someone your child who is not biologically your child, and you have not formally adopted them, you NEED a will.