As a rule, we don't let our kids have soft drink at all, except when we go out they have a glass of lemonade or raspberry. While I don't agree with what others do, I genuinely think they don't fully realise the harm it is doing to their children, or else why would they give it. I do think in the case where the child has become ill because of her diet, that if the parents refuse to follow Dr's orders, then it is a form of abuse. It would be the one case where I would say not to let the child get the upper hand over you and give in to them.