Giving Baby real food

Hi ladies I need your opinion on this topic, ever since my sister has her first baby she hasn’t really being listening to me in regards on feeding the baby food, when her baby turned 6 months old the pediatrician told her she can now feed her baby solid foods and she can give him home made chicken, but she got carried away she feeds him spaghetti, fries, candies, chocolate cookies, saltines, soup, etc, she feeds him like if he’s already one year old, and she give him juice, and cow milk, she now rarely gives him breast milk which before she was exclusively breastfeeding him. It’s driving me nuts, but that’s just me I don’t know what you guys think? I’m currently exclusively breastfeeding my 4 month old and I know I have to wait until 6 months to give her solids but I will only feed her baby food not “human” food.