AZR opens with the ancestor who corroborates the genealogy document:
"In the year 5595, the year of the panic, the father of my grandfather (on my mother's side), R. Alexander Ziskind son of Rabbi Meir Brook of Lyady, arranged a match with the town magnate R. Moshe Markovitz, known as Moshke Chiminoar (the synagogue in Lyady, Chiminoar, is also named after him)." AZR, "Uncle R. Yitzhak", "Memoir Chapters"; Project Ben-Yehuda.
The name R. Alexander Ziskind son of R. Meir Brook of Lyady, the ancestor after whom AZR was named, on the maternal side, is corroborated here from a primary source, consistent with the document "The AZR Genealogy". A marriage tie with the Markovitz family ("Chiminoar"), magnates of Lyady, is also documented.
R. Meir Brook is the last ancestor in this line whose name is documented; AZR does not name his father. Going deeper depends on the Lyady revision lists (NIAB), just as the missing generation on the paternal side was broken through.
AZR describes a child marriage — Rivka (age 11, of the Brook side) and Leib (age 13, son of R. Moshe Markovitz) — who were married "at their fathers' command" because of "the panic": fear of a decree that unmarried children would be taken into the army, "which brought many calamities upon the Jews".
A dispute (apparently over honors in the synagogue) led R. Moshe to order his son to divorce Rivka; the divorce was arranged by the halakhic authority R. Lipa ("mentioned in the Kuntres Acharon in the Shulchan Aruch of the Rebbe of Lyady", a Chabad work). Rivka refused to return to her husband, and married R. Yitzhak Rosenfeld. And here comes a rare piece of human testimony:
"When he learned of the circumstances of his divorced wife, his compassion was stirred, and he would send her, week after week, every Thursday, by the hand of his trusted man, ten rubles for her livelihood — and this he did for eighteen years. He never saw her face and she never saw his…" Ibid. (on Leib Markovitz, her first husband, who supported Rivka anonymously while her second husband was abroad).
"Uncle R. Yitzhak" himself, R. Yitzhak Rosenfeld, son of R. Shmuel Rosenfeld (author of "Mishpachat Sofrim" — "A Family of Scribes"), was "learned in Torah and wise, and engaged in commerce" in Vitebsk. AZR describes a financial fraud: R. Yitzhak exploited a government bank in Kiev (a 30,000-ruble guarantee through a fictitious "merchant"), lost everything and fled abroad for 18 years, until a pardon. On his return Rivka refused to renew the marriage, with dignity:
"You have come back after eighteen years; the days of our blossoming have blossomed and are gone… You are the father of my children. You may delight in them… but know that I am not your wife and you are not my husband." Ibid.
"I myself still knew my uncle Rabbi Yitzhak. He later became a contractor on the railway construction near Kharkov, and to him I owe thanks for helping me move my residence from Belgorod to Poltava." Ibid.
Uncle R. Yitzhak helped AZR move from Belgorod (Kursk Governorate, where he tutored Eliezer Margolin; see "The First Jewish Legion") to Poltava, a pivotal station in his life. Thus the maternal line is tied directly to the course of AZR's life.
The R. Yitzhak Rosenfeld here (merchant → railway contractor) is not identical with "my uncle R. Yitzhak", the Misnaged Torah scholar of "Among Hasidim", the one honored with the second chair at the Rebbe's table. Apparently two different uncles named Yitzhak (distinct surname, occupation, and character). Distinguished here so as not to conflate identities.