No smacking it doesnt work and is teaching them it is okay to do it to other children, they do make child leashes , put it on her hand attached to yours, do not take her out without it she will learn not to do it.Speak firmly to her,and if you are at home sit her on a chair in a time out, no yelling quietly if she gets off the chair take her back no words she stays there till she is good. Good Luck to you ..