A question I might try to touch on in a future book would be how the New York City-born Jewish songwriters of "It's the Most Wonderful Time of the Year," Edward Pola (Sidney Edward Pollacsek) (1907-1995) and George Wyle (Bernard Weissman) (1916-2003), might have been exposed to the tradition. Both men appear to have been living in California in the early 1960s. Some searching on ancestry.com indicated that the former’s father Alexander Pollacsek was from Hungary; the latter’s, David Bernard Weissman, was from Romania.

Had the writers learned traditions from Christian friends and neighbors in the US? Were they familiar in some way via their ancestors in Europe, given that Hungary and Romania had some ghostly Christmas traditions involving witches or goat-men?

Those things are possible, but credit might go primarily to Edward Pola, who spent much of his life in England between 1926 and 1961 at least, if not longer.

“GRANADA TV NETWORK have announced that Eddie Pola has joined their organisation as executive producer of light entertainment programmes.
“This appointment is the culmination of a career which started in England in 1926 […]
“Despite his travelling to and fro, the majority of his theatrical career has been spent in England and his family life has always centred here.
“Eddie Pola Joins Granada.” The Stage. June 16, 1955: 9 col 6.; "Eddie Pola Leaves Granada for U.S." The Stage. July 13, 1961: 10 cols 2-4.

Even one who had not spent time in England could have been aware of the tradition, however. As I’d noted in the introduction to the Valancourt Book of Victorian Christmas Ghost Stories volume four, aside from British publications being sold in America as well, and Americans republishing British stories, some Americans wrote stories in the tradition as well. The anthologist Edward Wagenknecht, writing in 1949, thought that American examples were “few and far between,” but he couldn’t have dreamed of the search tools we have today. August Derleth, more grounded in horror literature than Wagenknecht was, showed more awareness, writing under the headline “U.S. Revives Ghost Tales for Holidays” in 1945 that there was

“abundant evidence that the American reader is finding a great deal of pleasure in this form of entertainment. […] The telling of those stories at Christmas Eve as well as at Halloween is a time-honored tradition in America as well as in European countries, if admittedly not as wide-spread as it is across the sea.”
Derleth, August. “U.S. Revives Ghost Tales for Holidays.” Chicago Tribune. December 2, 1945: 20 col 5.