Worried about my sister going to school?

My half sister came here two weeks or so ago from the Philippines. I haven't met her for a while. I just turned 13 but in 7th grade and my half sister is starting school tomorrow in 8th grade and is turning 14 in a week or so. I know I can't stop her from going to school but I need advice. Okay well she's always want more attention than me so she's like competitive kind of even though I don't get much and not trying. Anyway when people are like who's she or new girl or looks at her cause she's new shell think she's getting more attention and think people think shes 'hot' (no offense she's not that pretty but it's annoying when she tries to hard it won't make her be pretty) and shell brag to me. The other thing I'm worried about is that she might want to steal my friends not because she think she cant make any she just want to make everybody like her better than me. Advice? I dint want really want to know why she wants to to this ( you can say that still ) but how to stop her and payback and show how I feel other than steal her friends or tell her. I will tell her when time is right but what can I do without telling. Pls don't be offending or unhelpful. Thanks