I agree with the previous poster-take the grandparents with you to the next appointment. O find articles on line to support your concerns and show them to the grandparents.
Make sure the grandparents know what a accurate portion for a two year old is. You don't want her to associate the treats with love and attention. She may be eating too many snacks, (I am surprised when I read the calories on some snacks when I am packing my kids' lunches) and then being served large portions at meals, all adding up to excess calories.
If there is a weight issue developing, I think it is best to address it now.
Try not to let your daughter hear negative comments about her situation so it doesn't effect her self image as she gets older.