We are in the same boat. My DD9 is DYS and DD12 is MG.
There was a time that my DD 12 struggle with the idea that her younger sister is smarter than her and know more than her. I spent a lot of time with my older DD and made sure that we love them both the same. We tried to slow my younger DD down (just let the public school handle it :-) for a while).
We are still trying to make sure that both DD gets equal amount of time from us. My older DD is at peace with it now. Both being girls have its own challenges as boy and girl. But they are each other's best friend (especially playing minecraft- younger DD will help her big sister with new stuffs).
Just like ultramaria, whenever we see big sister has something that she is better at it, we make sure to complement her on it and encourage her to teach her little sister.
