Dear Prudence,
I'm a grandfather with a 4-year-old grandson who is smart and engaging, but who frequently throws tantrums when frustrated. My daughter-in-law’s mother cares for him during the day while she and my son are at work. Several times a month I pick him up from her house so he and I can spend time together. Usually I feed him lunch, but the other day he refused to eat. When I took him back to his grandmother's house, he immediately announced he was hungry. She said it wasn't snack time for another hour and he should have eaten at my house. He launched into a fit, which escalated into a shouting match between the two of them. She put him in time out then made him drink sips of vinegar until he stopped screaming, which I believe is a method she used with her own numerous offspring when they were young. When I went to say goodbye he was huddled in a corner, mouth reddened from vinegar, shuddering and whimpering "I want to go home." I am deeply disturbed by the whole incident, and feel I should have done something, but I don't know what. I also don't how to raise the incident with my son or daughter-in-law. Unfortunately, I have a feeling they will say the grandmother handled the incident appropriately. Please weigh in.