Hermanastros o algo más

You already knew that your father was dating a woman but he had never introduced her to you until one night your father told you today you will meet her, it's exciting and you went up to your room to change, the night arrived.

Father-son come down, they've arrived.

I went down and saw two handsome guys and a woman.

—Ah, hello, nice to meet you.

Tom—Hello, also.
Bill—Yes, yes, a pleasure.
When they passed by, the twins sat on the couch and talked something that only they could hear.
Tom—How good it is.
Bill—How old are you?

Hey I'm here

Your parents had Divorced more than 3 years ago, in one of those 3 years I met Mrs. Kaulitz, she had two sons, Bill and Tom Kaulitz, they were very handsome. Your father introduced them to you one night and you fell in love with them, but they are just your *Stepsister or something else. * ??