If the story is not a newspaper fabrication, then the infant could be any of the 30 or so that did not survive~ the stories of those that did survive being fairly well established. It was not Mrs. Docherty's baby, nor was it that of Mrs. Wickings-Smith or Mrs. Cox. 99% certain it was not the Booth infant, either. So, if Father Maturin's last noble gesture in fact happened, it has an element of futility to it because he placed the infant into one of the boats that was wrecked.
But, to me, this story always seemed one of those too-pat-to-be-true disaster tales that spring up around prominent figures who die at sea and who, therefore, are not around to contradict them. If he went to the nursery, why did he take just one baby? Was removing just one baby from the spot where its mother would be most likely to go in order to retrieve it something a man who had witnessed death many times in his career and who, as a result, was probably not operating in a blind panic would do? Barring intentional abandonment~ always a possibility~ it is not realistic to expect that the infant became irretrievably separated from its mother or caregiver on the boat deck. Unlike toddlers and older children, infants cannot get caught up in a crowd and stampeded away from their caregivers, and although things were chaotic aboard the
Lusitania, condtions were not such that a mother who dropped her infant could not bend over to retrieve it. Just as Mrs. Cox did. And, "Find its mother?" On the surface it seems like a brave statement, but when one thinks about it, the first response is "how?"