Should I text him?

My sister is 16 years old and my mom has been having trouble with her. She is almost never home and when she does come home she doesn’t talk to anyone. She has flat out stole money from me and lied to both me and my mom as well as accused me of lying about stuff that she’s done. She has shown up at my work twice now and caused a scene while I was working. I’m going through my own stuff (see other recent post on my page) and don’t have the time or patience to deal with her. Today when I went to talk to our cousin who we both confide in about our relationships about what is going on with my boyfriend and his medical situation they informed me that there is a lot more going on with her. My sister’s boyfriend had called this cousin to tell her that my sister has been stalking him on through his phone somehow and showing up wherever he’s at. He is trying to get some space from her and she’s not giving him any. She is always at a friend’s that lives down the road from him house. We can’t figure out how to get her to come home and give her friends some space.

As soon as I found out about her stalking him I immediately knew how. He is always on Snapchat and has his location on. She has been going on just to see where he is and going there. I have his number for emergency because they used to switch phones a lot when school was in session. He doesn’t have mine though. Should I text him to turn off his location on Snapchat to help him out so he could get some space from her or just let her keep doing this and let the cards fall where they may?

Update: I texted him and he called me. Over the next few hours following he blocked her and all her friends and family on all social media accounts. She isn’t talking to anyone right now after our cousin confronted her about stalking him after he blocked her. My mom also talked to her and she wasn’t really talking just crying and answering questions with the quickest response she could give. She’s staying at her dad’s house until Sunday night and I doubt I’ll hear from her. I think but I’m not sure that once she realized he blocked her she called him and they broke up.