What do you think....?

My Dad and his GF just announced their engagment. They told me and Sabrina (her kid whose my age) at different times seperately but now they want us to go out to dinner tonight. I really like Kelly, the GF, and the news hasn't come as a surpirse. I guess i'm cool with it. I don't know the details, like when, where, where we'll live. I find out tonight. But Sabrina, is my age and the head of the snobby popular crew, i'm popular, but the "nice popular. Well every time we go out she like spends the whole time texting. She like never says anything unless directly spoken to. She just really bpthers me, i mean she is so rude, but i know if were going to be sister (step- sisters) The best way to start a relationship isn't by getting in a fight. What can i do to not be mean but get my point across. And i know this sounds stupid but who has spent all their life with one parent (a dad) who you are really close with and then all the sudden have a step mom, whats it like?