Yammy
I have the same problem with one set of GC. One lives on peanut butter and choc chip ice cream and will starve all day until someone gives in. not me I might add. The sibling was like this but now tries what they think is," grown-up food," steak, duck, broccoli, etc.
The one from the other family who attended nursery from a very young age just says I'll try and if I don't like please may I leave it.,I feel this is alright and they have quite a varied diet.
I think we see this from the "stressed adult" side of things but what about the "stressed child"?
You say "until someone gives in, not me I might add" as though this is a good thing.....IMO there shouldn't be "giving in" because it shouldn't be any kind of clash.
