Adoption Confusion?

Travel Info
This is confusing... Pay attention > I live with my grandparents. My younger sister was taken away from my mother and placed into a foster home. Her foster parents ended up adopting her, however it was an open adoption. She and my grandparents have remained very close to her. We have also become close with her new parents and new sister. My grandparents treat ther other 2 girls like they were their grandchildren and I treat them like sisters. When talking to my friends, or when asked about siblings I am always confused about what to say. They are basically sisters, but should i call them that to other people?

Travel Tips

I would have to agree with Jessica's answer. If they feel like sisters then feel free to say that. If it is a little off for you then you could always tell folks that you have 1 sister and 2 step sisters and your really close to all of them.
Others

if they feel like your sisters and you're emotionally tied to them, then i would tell everyone that they're your family and sisters.