i know the feeling i have 2 girls 5 and 9 and to be honest the tantrums and stubborness from you d is normal in a way my advice would be to tell your s to ignore her and keep ignorig her boredom will make her stop, as for public places, when she gets bad look at her and whisper "everyone is watching you and they think you look really silly" it will or should make her stop and think ive done it and it works.

vicky x

This great book might help 'Siblings without Rivalry' by Adele Faber and Elaine Mazlish. Hope it works and good luck