I'm guessing that something is not working well for your sister ?? That is making you concerned that she will not be capable of caring for a child ? Will she have a safe place to live before and after the child arrives ?? How about medical care.

I think it is really great that you want to support her during this critical life changing event she about to experience. She is probably going to need all the help she can get. Plus - you will have the opportunity to be an "Aunt" and thus an important caring adult in the life of a child.

Perhaps you can research on her behalf any local agencies serving young women who are in her situation. Perhaps you could drive her to appointments and just be there to help.

best of luck