So, for some background, my little sister is 16, soon to be 17. She has bipolar/manic depressive disorder, ADHD, ADD, and is a habitual liar. She's been on meds since about 5 years old. My grandma bough her a phone when she turned 16 and put her on our phone plan because she was behaving well. Recently, while living at my moms, she ran away to voluntarily be part of a human trafficking ring orchestrated by a man who said he'd leave his family to be with her if she met up with him in North Carolina, which she did (a 5 hour drive from my location). She threw the phone out the window of an Uber that he called for her and she met him. We got her back and after everything was said and done, my mom didn't want her to live with her anymore, so, with no other option, we opted to have her stay in our cramped 1 bedroom apartment with me, my other sister, grandma, aunt, and 4 dogs. It was ok at first. She took her meds and everything was fine. Then, a neighbor of ours gave her an old phone she had, which we told her not to do, but she did anyway. Along came Snapchat, (the main source of the problems) Instagram, and all the other social media a 16 year old could get their hands on. Eventually she started to sexually exploit herself to random men and kids her age online. We confronted her but she is a very aggressive person when not on her meds (which she wasn't). After that, it was like walking on eggshells every time we walked in the house, especially around my other sister who, on multiple occasions, she tried to kill, and I had to protect her. We let it continue until recently, when she dropped her phone in the bathtub and it died completely. She was extremely mad about it and my family didn't have much to say about it. Before I continue, she gets disability in my moms name until she's 18 and proves stable enough to have the money to herself (she isn't), and my mom gives my grandma $300 a month to spend on clothes and things she needs. It was fine until today. She smokes weed, which isn't a crime, but it is if ur underage, and my sister and I grew up around a lot of drugs and we don't like having it around the house. So, she claimed today that our mom said she could get another phone with her money, but she didn't. But, my mom shorted her about $40 because she had an extra bill she had to pay. My little sister got mad about it and had an argument with my grandma (who's been nothing but supportive of her) about the whole thing. My grandma didn't push, she went to take my sister and I to work and do laundry. She picked me up from work and when we got home, my little sister started in on my grandma about how it was her money and she could do what she wanted to with it. My grandma bit back and it was a big screaming match for a few solid minutes. Eventually, she went outside and went down the hill to another apartment of a guy she talks to and started yelling about how we were horrible people and that we're toxic and that she hates us. It's coming to a point where we're afraid for our dogs and ourselves. We don't know if she'll hurt us or even kill us. My biological father has everything she has and he came close to murdering my mother and my sister a few times. My mom wants nothing to do with her anymore, which is understandable, but every time my grandma calls her with an issue about my little sister, she brushes it off or tells her to call the cops. My grandma and I both agree that she's family and we love her no matter what, but there comes a breaking point in all people and we've all just about met ours. It's always constant having to be carefully what u say or do or else she'll blow a gasket. It's getting out of hand and my grandma has consider for a few days now is she should give her rights to the state (she has physical custody). I don't want to give up, but at the same time, the safety of my family is at stake and we don't know what to do anymore. Any advice would be greatly appreciated.