Q: In a recent column, you advise that stepparents have complete disciplinary authority over all children who live in or visit the home, but do you feel the same policy should apply when the stepparent joins the family when the kids are teenagers instead of younger children? A: Your question is of great importance in a parenting culture where so many parents are bringing children into second marriages. It is also important for adults in so-called stepfamilies to understand that the majority of mental health professionals are giving decidedly bad advice concerning this issue: to wit, that parents should only discipline their own - as in, biological or adoptive - children.