in a private exchange of messages, a member of this group suggested that I share with the group more detail about what I found. I'm therefore copying/pasting from my response to that member to the entire group.
Thank you very much for your kind note and suggested resources.
I must share with you that I had no intention whatsoever of lifting up corners of rugs in Polish history or anywhere... I was following a very interesting genealogy where it led. BTW, it led also to the Maharal of Prague, the Ba'al Ha-Levushim, and even to Rashi (not directly). Once I saw the name of Rashi, I went over to Wikipedia, where there's a statement that his lineage cannot be proved because of a "seven-generation gap" after the expulsion of Jews from France under Philippe le Bel. Well, there's Rashi in the tree. I didn't bother to look further into his direct lineage, but there is certainly a continuous set of links that includes him going back, purportedly to Venice of the first millenium CE, and even farther - if it is to be believed.
Do you know any about rabbinic lineages? There seem to be several, specially tagged, in this tree.
From my comments you may have gathered that I have some background in history and historical method. That's true, especially in the history of Russia and what we used to call Eastern Europe. The latter is a little spottier but it's by no means trivial. One of my favorite genres of literature, both fiction and non, is the role of falsehood in history - e.g., Barbara Tuchman, Umberto Ecco...
What I find fascinating about genealogy is precisely where it leads you historically, if you're at all curious. I wasn't happy to find what I found about that day in March 1612...
I'm probably not going to pursue these leads (and I actually came across some of them myself), but am most grateful for your message and your interest.