OK, I shall abide by the decision of mumsnet:
Background> 3.5yr old DD1 is a nightmare eater. She likes hotdog sausages, chicken nuggets and jam on toast - I don't offer these often so most meals involve screaming and crying (and thats just me!).
So MIL and SIL bought her a bottle of Yazoo strawberry milkshake and served up the entire thing for her (500ml). She drank the lot as she was thirsty and it was tasty, one minute later she was crying as her stomach hurt, and of course she didn't eat any lunch as she was full. This is the most milkshake DD has had in one hit, but she is always being given large amounts of milkshake, and other unhealthy food, at MILs.
I have been considering banning ALL snacks and drinks (except water) between meals to see if it improves her eating at mealtimes, but am worried this might be the wrong thing to do - DD is a bit of a natural grazer and has healthy snacks (healthier than meals sometimes!) with me and my mum. Just not at MILs.
Would I be being unreasonable to object and tell MIL and SIL to stop giving her milkshake, or at least limit it to one SMALL cup a day? Am I being PFB? They are doing me a favour looking after DD, and OH pointed out this is how he was raised, but it drives me mad and really is not helping my never ending battles over food.
BTW MIL has her 2 mornings a week while I am at work, plus MIL and SIL have her all Sunday.