Because I like responding to my own posts :):

I found no less than five TOWNS called Dymarka/Dymerka in Ukraine and Poland! At least one of them is near the towns that Harry Friedman's wife Sarah's family was from. A clue! Possibly they lived there or had family there or something that gave rise to that story.

I've also since found that Harry's father's name was not Alexander, but David. Baby steps!