Child nutrition

I would like some advice. How can I tell my mother in law to stop giving my daughter candy it seems like she’s constantly giving her candy I’ve tried telling her please offer her food fruit veggies something first but seems like she doesn’t listen. As soon as she has the chance she always offers my daughter a bottle of milk she’s almost 3 (I tell her please offer her food first) but what bugs me the most is that she always has to give her chocolate milk & if there is no milk she puts sugar in it. Idk how to get get my daughter to eat anymore because she just wants sweets.