I saw my baby, crying hard as she could cry.
What could I do?
Crystalline tears fell from chubby cheeks of Rose Weasley. She was still considered a babe nary two years in age.
My baby's love had gone and left my baby blue.
Ron didn't know.
Rose was in a fugue state. She was upset with her mother. Replacing her with another baby. There were signs. Like the writing on the wall. Literally, Rose had written her feelings in crayons on the wall in last ditch effort to get through her father's thick skull. Alas, Ron didn't notice. He never did notice things in house unless it was related to food or quidditch.
However, Hermione did notice. It was a delicate time for her; hugging the loo was her major activity of the morning, afternoon and evening. She finally found time to talk to her first born.
But what kind of magic spell to use?
Love. Maternal Love. No foolish wand waving necessary.