You stated that one of your children died. The child has one adopted child and another child that was adopted by her step-father. Your child was divorced. The deceased child did not leave a Will.
If your Will provides a right of representation meaning that if a child dies and has children the deceased child’s share goes to his or her children.
If it does not, or if you want to change your Will, you can do a codicil or a new Will and leave the property that you had left to the child to someone else.
If there were no Will, the child he adopted would stand in his shoes and receive his share of the estate.