Don't know if any step-moms encounter such step-daughter and what should I do since we live under the same room everyday.

One of my step-daughter is 12 years old now and soon this year she will be turning 13. Another younger one will be 9 years old by the end of this year. I'd like to talk the older one here.

Background : married 3 years & live together 3 years. Their mom passed away 6 years ago.