Tiffany

She constantly has snappy comebacks to everything, she's bossy and mean and yells at her older brother who is 8, she's bossy to other children. She is 6 years old going on 16. She talks back, I sometimes feel like I can't handle her. Does anyone have any suggestions on how I can teach her to treat other people with respect and not have such an attitude or be mean all of the time? Before you answer please note that I will not smack her, grounding doesn't work and neither does eating a bar of soap. Also, please don't say "it only gets worse" because when I ask for advice that's all people tell me. My son doesn't act that way...is it only girls? I need help, I'm at my whits end.