It may be a good idea before you think of discipline to try to figure out the Why shwe is doing this, could she be feeling left out, is she jealous of her little little sister she sees her getting more attention,? Maybe focusing on her postive side and prasing her when you see her doing something right. Some one to one time, let Dad look after the Baby, then ask him to play games with her, she used to be the Baby of the Family its hard to relinquish that . Time outs work at this age , if she is misbehaving put her on a seat somewhere and tell her to stay there till she is sorry, if she comes off put her back, be consistant and do it quietly do not get into any confrontation with her.Good Luck,