I had this same issue growing up in care and I was able to talk with my caseworker and let her know that it important for me to have a relationship with my only bio sister. I explained she is not a bad influence she just aged out, thats it. My caseworker then elevated my concerns to my lawyer and the judge granted visitation rights and phone calls for my sister and I. So I would advise you to take it to your caseworker and if they cant help try and ask your lawyer, CASA, anyone you trust to represent your interest. You have that right to contact anyone representing you in fostercare. Lastly look and see if your state has an Foster care Ombudsman. Type in google Oregon ( whatever your state is) fostercare Ombudsman and get the ombudsman contact information and reach out and explain your case. They will help you! Good luck!