I think you should say firmly NO you will not behave like that and if she caries on screaming blue abuse at you because her juice is in the wrong cup (the right cup happening to be my ds's which he is using) then she goes without juice and gets taken to the naughty chair/step, if at that point she is still rolling around and screaming and trying to kick and spit at you i would smack her bottom YES SMACK her bottom, she needs to see you are the boss and not just someone to be 'tested'!!!!! enough is enough!!!!!