I have to agree, I think you should let your daughter take her cup in to school, it is more important that she gets a drink at school and it is unlikely that children of 4/5 will poke fun at her, even if they do this may be just the thing to get her to stop using it and move on to more grown up cups. It doesn't however solve your problem with other drinks I guess you will just have to keep trying. This is her way of being in control. Good luck.