Not watching my baby!

So my husband's grandmother constantly feeds my nieces things they should not eat. They are both lactose intolerant and she gives them cheese and milk all the time, but when they're stomachs get upset and they start crying she yells at their mother, and tells them to shut up. She also gives the youngest one (9 months) tons of caffeine and soda. I honestly don't know if it's the hormones that are making this seem like a big deal but it makes me so mad that she just doesn't think about the things she is doing with these babies.