I'm 20 years old and my boyfriends kids live with us part time (3 kids) ages 15, 13 and 8. Lately I've been so stressed out because I don't have kids of my own and I don't really know how to dicipline someone. The 15 year old is rude and always has an attitude, hardly talks to me. Which is fine, she's probably going through her little phases. The 14 year old is sweet (SOMETIMES) he listens to me and obeys me, but I sometimes catch him slipping when his older sister encourages him to misbehave. The 8 year old is a very sweet girl, she also listens so them two aren't a problem. But I really can't stand the 15 year old girl. She always has something to say and treats the little one like crap and for some reason I always stay quiet because I feel like I can't do it. She's just so hard headed and even though my boyfriend has given me the privilege to dicipline them, I just can't tell the 15 year old anything because when I do, she's extremely rude. Since I'm only 20 she feels like I shouldn't be telling her anything. I don't know what to do anymore. I'm so stressed out and I'm also expecting my first baby (26 weeks) it's got to the point where I'm always in a bad mood and wish I had the balls to actually say something to her. What do I do when she's mean to her little sister, what do I do when she's rude to me or just rude in general? At first she was good but lately she's just been worse. When her dad tells her something about me she doenst even care and she won't hide it. I tried being nice but I'm so overwhelmed now. I really need some advice please...