Now I've got VWML up again I was able to see the Janet Blunt papers and there were 2 or 3 more songs from her (all Christmas related I think) that didn't come up in my Roud search earlier, including a version of Sing We Merrily! It has tune and one verse by the looks of it. It's late for me to poke around with now, but I'll have a proper look tomorrow.