C.D.
You have to be in charge! You say that you want her to know that she can't do those things to her brother, but why is she doing them to you? My little girl is 4 and does not use the words shut up, they are naughty words especially towards you, her mother. Take control! Have you tried time out? If she will not sit there on her own, hold her there, she will learn as soon as you show her you mean business. You have to give merit to your words and make punishment believeable. Spanking is not illegal either as long as you are not spanking hard enough to leave a bruise. There is also the options of taking away her favorite toys, tv, or whatever amuses her the most. I know it is very difficult being a single parent, I have been there. But you are hurting yourself and her more by not putting your foot down. Good luck and hopefully no offense!