The uniforms are not typically just "any white button-up shirt", they have to be purchased from a specific uniform supplier. You can adjust a shirt to make it smaller, but not larger. She'll need to buy a new one.LOL idk if it costs extra to adjust/buy a new version but other than a super unique looking uniform/customized to the school, feels like it should be easier to find a shirt the next size up if it's just a white button shirt,