Most of us love our children dearly, but they can trigger our upset like no one else can! Feeling disrespected or unappreciated, we may shout, scold or threaten our kids, despite desperately wishing we could keep our cool.
It is terribly awkward to deal with a child's upsetting behavior without stepping on the toes of her parent. Your situation is even more challenging because you wisely understand that this little one is both mimicking her mother and acting out her hurt. Here are my thoughts.
Your family is going through significant growing pains, with everyone having to make some big adjustments. Rather than giving you suggestions for controlling your stepson's behavior, I think it best that we step back and look at the situation from a bigger perspective.