mother on drugs

I have two step daughters and am now 11 weeks pregnant. My step daughters' mom has been on drugs for a very long time and is homeless. Last August we found out she was pregnant and tried to help her but she kept shooting up. We took her to detox and did everything to help her get sober but nothing worked.

She is two weeks away from delivering and has begged us to take the baby. She said she will just leave the baby at the hospital if we don't take her. My SO's mom has asked us to take the baby because as the grandma she wants to make sure all thtre sisters are together.

I know that we have to take the baby but man my emotions are all over the place. I am pregnant and we are crazy busy as it is. I am also in college and my SO works 10 hours a day. I said that if we take the baby then she has to relinquish all rights to the kid because it would be too hard If she didnt. I am also worried what effects the heroin has had on the baby. She hasn't been to a doctors appointment since 18 weeks.

Ladies any advice at all.