What do I need to know about my minor sister living with me?p

Hey everyone. I am looking for some advice if possible. My mom is being forced to sell the family home which is leaving her and my 4 younger siblings without a home. She’s working on what she will do once she receives her half of the money (apartment, down payment, etc) but the in between is what makes us nervous. I will be taking in my sister. She is 14, a freshman. She gets along better at my house than moms, but that’s just the classic mom/daughter bash of teenage years. Has anyone gone through this? I will not be taking custody, but will my mom need to grant me guardianship? How do I enroll her in school? What will I need? Should I just call the district that we are in and begin that conversation with them? I’m just so confused and yes I have googled it lol, there’s just so much on the internet. I just want to be prepared for when things start to go into motion so I’m not just a sitting duck- and I need to plan ahead.