My grandmother was subject to a less-severe form of this abuse when she was a child. Her father had remarried after her mother’s death, and the new stepmother had two children of her own.
My grandmother and her brother and sister were only allowed to eat the scraps after the father, stepmother and her children had finished eating. If the father brought home ice cream, only the stepmother’s children were allowed to have any, and the leftovers were carefully policed to make sure my grandmother and her siblings didn’t even get a taste of it.
The stepmother’s children had the finest medical care money could buy, but she wouldn’t permit any treatment of my grandmother or her siblings. By the time she married at sixteen, my grandmother’s teeth were completely rotted away. (The first thing her teenaged husband did after they married was buy her a set of dentures.)
She doesn’t like to talk about it, even after all these years, but I asked her once what her father did, seeing his new wife half-starve and neglect his children’s health. She said he basically ignored it in favor of peace, because the stepmother became enraged whenever he paid attention to his own children.