I don't even think she should be having underarm hair that early. This is too young, but since she is young, she will be wearing tank top and stuff so she will want hairless arms. DO NOT SHAVE! Her underarms are gonna get dark and her hair will grow back more, longer, and thicker.She needs to wax or epilate. The good thing that comes out of waxing and epilating is that it gets rid of the dark underarms, it pulls your hair out all the way so it will feel smoother, and you don't have to do it everyday. Shaving gives you black underarms, only cuts the hair off, gives you a rough feeling, and you have to do it everyday. So epilating and waxing are the best things to do for underarms. I don't want your stepdaughter to go through the dark underarm thing like mostly everybody else.