Question about FS classes

Hello, I have a question. And my car is registered to my mother so far. So I have 30% and can save a lot. However, I should let the car run on me now, because my little sister (driver’s license newer) also wants to register a car. I have had the driver’s license for 8 years now. Would I get up in the SF class and not start at 140%? If so with which? Another idea: I take over the percentages of my mother (f) All this makes my insurance) and my mother then registers my sister’s car. Since she has had the driver’s license for over 20 years she would have to start with less percent. Is that right? If so, how many percent would she start?