And Paris, whose family was told she had neuroblastoma when she was just nine days old , said she too feels a kinship with Tiny Tim, whom she plays in Chicago. “We both have difficulties walking, but we’re still happy all the time.”

For their parents, the opportunities stir a mix of emotions. In one of Scrooge’s visions, he sees a future in which Tiny Tim has died. Jonathan’s mother, Tiffany Rizzo, noting that her child’s prognosis is uncertain, said that scene “was really hard to watch — it does hit close to home.” But, she said, “For Tiny Tim there’s hope,” she said, “and we have hope for Jonathan.”

Matthew Warchus, a Tony winner (for “God of Carnage”) who directed the London and New York productions of Thorne’s “A Christmas Carol,” said he is mindful of how the young performers are seen. “The admiration mustn’t be condescending,” he said.

But he said the message to the audience is important: “It opens our eyes and our imaginations to all the different versions of human beings that surround us, and that’s a good thing. ” (Warchus is also protective of the child actors: he refused to let them be photographed playing the role, which they do in alternate performances, saying in a statement: “It would be unrepresentative and unfair if an image of just one of them were to be published.”)

Tiny Tim has long been a character of concern for disability advocates, in part because of his high visibility. Dickens describes the child’s condition with pity: “ Alas for Tiny Tim, he bore a little crutch, and had his limbs supported by an iron frame!” He is best known for his benediction, “God bless us, every one!” which continues to prompt tears.

“Other characters fall by the wayside and contemporary ideas take over, but this story is so persistent,” said Julia Miele Rodas, a disability studies scholar and Victorianist at Bronx Community College. She said many advocates dislike the symbolism of disability represented by a helpless child. But she said Tim can also be seen “as kind of subversive, because he’s the one who empowers the change in Scrooge.”