Private User,
My main observation regarding the difference in birth estimates, i.e. 1590 vs. 1620, is that the two estimates are basically a generation off from each other. Depending on which father is the correct one, Dinah becomes either a granddaughter or a great-granddaughter of Saul Wahl, which is also a difference of one generation. So, it seems pretty likely to me that this is at the source of the 30-year discrepancy in birth estimates. That is really what I was trying to say in my last post, in case I wasn't clear.
Regarding the pertinent conclusory remark you mentioned, I will provide the full context, complete with sources and rationale, so that it can be better understood.
The main text for which the reference is supplied comes from Chapter 1, page 29, and is as follows:
"G5.1 Judah Wahl's, married the daughter of Moses Reb Lazer's of Brest-Litovsk (that is son of Eliezer Isserles who was a cantor in Cracow and died there in 1623, brother of the ReMa)."
Footnote #56 is associated with this passage, and reads as follows:
"See AAL (end) and IV, 33. DK states that it was Judah son of Pesia (G14.12) who married the daughter of Moses Reb Lazer's. See also Ir Tehila, 31. Sources that claim that Saul Wahl had a son Judah Wahl (such as Edelmann in Gedulat Shaul) are incorrect. See the discussion in Neil Rosenstein, Saul Wahl, 2006, 265 and Avotaynu XXII (2006), 2, 26-28. The relationships presented here explain how R. Saul of Cracow, son of R. Heschel of Cracow was able to call R. Saul Gunzberg of Pinsk his first cousin (sheini b'sheini) as is discussed in Chapter IX - under R. Abraham Joshua Heschel of Cracow. Special thanks to DovBerish Weber for his clarification of confused ancient sources."
When I go to Chapter 9, I find the part where it says that dinah was a maternal granddaughter of R. Moses Reb Lazer's, because her mother, who married Judah Wahl's, was a daughter of R. Moses Reb Lazer's. It goes on to say:
"Another daughter of R. Moses Reb Lazer's married R. Naftali Herz Gunzberg was the father of R. Saul Gunzberg, ABD Pinsk. R. Saul, ABD Cracow, son of Reb Heschel wrote and approbation (in 1705) to his uncle, R. Naftali Herz Ginzburg's Naftali Sh'va Ratzon where he calls, Saul Gunzberg, sheni besheini - that is - his first cousin. The two Saul's were not named for the same ancestor. See the image below of the approbation by R. Saul, ABD Cracow, son of R. Heschel to Naftali Sh'va Ratzon, published in Hamburg in 1708".
Okay, I hope this will be helpful in some way.
Claudia