How do i cope with my new stepsisters?

I know it is difficult, but you can either make the situation worse or you can make it better. They are babies. If you treat them like your family then that will eleviate some of the anxiety you are feeling. You are a big sister to them, but you are still a little sister to your other siblings and that will never be taken away. Have fun with the little ones and show them they can count on you. Having little ones look up to you can be very rewarding.