NC for this and will try to keep the details vague, but I could do with a bit of advice from people not involved.
DSis is single mum to DNiece late primary school age. Has always done drugs, quite disordered lifestyle, struggles to hold down a job etc. I got told by somebody I trust that they have very recently witnessed DSis smoking crack cocaine. DNiece was not in the house but I am confident that I don't know the half of it generally. This is the second time now that I've heard this. DSis has lost a lot of weight recently.
I am not particularly close to DSis although we do live close to each other- completely different lives/lifestyles, I'm fairly straight laced/got my act together. DNiece does occasionally come to stay and the last time she did, she looked awful - tired, grubby clothes. She is becoming quite withdrawn but I'm not close enough to pry really, however on hearing this I'm so desperately worried about what's going on at home. I know the house is a mess, DSis often has people round getting off their faces etc, either that or she's in bed on a comedown. She does currently have a job and I worry about the impact that any action would have on that.
So where do I go with this information? Talking to DSis won't work, have tried that in the past and she gets very defensive, insists she knows what she's doing etc. But this is a step up to another level - CRACK ffs. I am leaning towards social services. I just want what's best for my niece.