First a little background:
Jews in the Russian Empire were required to take Russian surnames as early as 1804, but surnames were not consistent within a family nor commonly used until after 1844. In Yiddish and Hebrew, the traditional “son of” form was used, even in government documents. For more detailed information, see the Avotaynu Online article here: Avotaynu Online - Jewish Surnames in the Russian Empire
After the Holocaust, family members across the United States tried to put together the family tree and to locate their cousins and aunts and uncles. That is the tree on the front page of this website. Sol Yudelson knew that he was named after his great-grandfather, and the family used his name, “Solomon Isaac,” as an Americanized version of our ancestor's name. Dorothy Saul Rosenblum called him the Yiddish sounding version "Shlame Yithok" in her history of The Saul Family published in The Southern Israelite.
After Lithuania became an independent country, more old records became available. We now know that Sol Yudelson’s mother’s grandfather was Solomon and his father’s grandfather was Isaac. Sol Yudelson was probably named after two of his great grandfathers.
Our family founder, the man we call Solomon Isaac Saul was born before Jews were required to take surnames.
He is identified with different names in different records.
In 1855 Shlomo Girsh, son of Zusman, owned a house valued at 200 rubles.
In 1877 Shlioma Girsh, son of Zusman, owned a wooden house on Shosseinaya street.
In the 1887 List of Residents of Jonava, Solomon Girsh, Zusman’s son, Solsky is listed with his seven sons as we know their names.
In the 1840 Taxpayers list for Jonava, Zusman Solsky, son of Girsh is listed as a carpenter with 3 adult males in his family.
This would mean that the man we know as “Solomon Isaac” was known as “Solomon Girsh, son of Zusman” in his lifetime, probably named “Girsh” after his grandfather.