Hello everyone has anyone got any advice my daughter is 17 months old and today she been hurting her baby sister i turned my back for one minuite and she hit her 6 month old baby sister then scratched her i told her off and showed her you need to be gentle with baby sister which she always has been even with her dolly shes gentle but today she has been very naughty and laughes when i tell her off and rolls her eyes at me has anyone got any thoughts on this please.