LONDON — If much of the world was captivated by the life and death of Charlie Gard, the incurably ill British baby whose parents waged a legal war with a hospital over his treatment, for Stephanie Nimmo, it was deeply personal.

Like Charlie’s parents, Connie Yates and Chris Gard, Mrs. Nimmo had sought experimental treatment in the United States for her daughter, Daisy, who had a rare genetic condition called Costello syndrome that made her partly blind and unable to speak more than a few words. She, too, grappled with the promises of alluring but unproven medical research and the dizzying array of armchair diagnoses on the internet.

The two sick children were even treated at the same London hospital, Great Ormond Street, which opposed the Gards’ court petition to pursue treatment abroad and, later, to bring Charlie home to die — just as it had thwarted Mrs. Nimmo’s request, six months earlier, to have Daisy’s life-support systems removed at home.

“Charlie was in the same intensive care department as Daisy,” said Mrs. Nimmo, a leading advocate for parents of terminally ill children. “It was shocking to see the crazy media circus and these parents stuck in the middle trying to save their child.”