Will My 17mos. Old Neice Be Taken Away From My Sister if She Seeks Drug Addiction Treatment?

My sister is recently separated from her husband. She and my 16mos. old niece live with my parents, who are supporting her in every way. We are concerned with my sisters serious drug addiction to pain killers, started after the birth of my niece. My sister has a fear if she seeks treatment, the baby will be taken away from her. Is this true? How could that be? If she seeks out treatment, and the 72 hours she is in detox, her family will be taking care of the baby.