Dealing w/Biomom

So our daughter who is now almost 16 is on FB and her biomom somehow got unblocked (she wanted her blocked for numerous reasons including drug use) and started messaging her, stealing her cover photos, profile photos etc and putting them on her own timeline. Well one day I was signed into our daughter FB account and up popped FB messages from her biomom. My daughter claims her biomom had told her "you are so beautiful!" and that started the conversation. We talked about it...my point was I don't mind her chatting with her but it needs to be monitored because biomom is a drug addict and very narcassistic (she has been diagnosed narcasisstic personality and biopolar and other issues). I'm worried our daughter will be hurt by biomom like her older sister who's 21 and has nothing to do with her now. I'm glad I have an open relationship with our daughter and it was easy to talk to her. Problem with biomom is she thinks her daughter is that 5 yr old naive child she lost. Luckily we raised a strong daughter who knows the truth (which our daughter has told us this herself). So they aren't communicating anymore....however now biomom is posting on her timeline on FB about stuff about "If anyone hurts or hurt my children I will kill them with a photo of a person holding a child and a gun." She's crazy! She is the one whom lost her 3 kids and she posts that? She needs to look in the mirror. I have no respect for her anymore. She tends to blame everyone else but herself for everything and her daughter now sees that. It's just crazy how you can act like that when all along you are the one whom didn't protect your children from abuse! So, now my concern is she turns 18, biomom decides to contact her again (somehow I don't know). I sure hope our daughter stands her ground and doesn't crumble under all the guilt biomom is going to throw at her. Anyone had to deal with these type of issues? Luckily she's still in Idaho and we aren't. :)