Thank you
@Vals_Garden for your input. Because I'm tremendously impatient, I had already taken it upon myself to finagle something with the begonia babies. I wound up just removing the leaf entirely, then cutting around where the pup met the leaf, stuck it in moist potting soil, put it in a sealed plastic bag in a lowlight window sill. After 8 days this is what they look like. There appears to be new growth and some kind of aerial roots? At any rate, they aren't dead yet!