R' Isaac Eizik HaLevi Weisman, A.B.D. Dukla

Based on his son R' Natan Nota HaLevi Landau of Oświęcim's yichus text, it is highly like that R' Yitzchak Isaac Weisman was the son of Jacob Brandeis from Uckange, France and was the grandson of Naftali Herz Cerf Brandeis, brother of R' Moshe Charif Brandeis, ABD Mainz.

The yichus letter states the grandfather's name was Yaakov who was a rabbi in Metz, and that Yaakov was the nephew of R' Moshe Charif Brandeis, ABD Mainz. The only sibling of R' Moshe Charif Brandeis who settled in France was Naftali Herz Cerf Brandeis, who was a rabbi who lived in nearby Uckange. The MaHaRaL of Prague Megillat Yochsin text dated to ~1718 mentions that Naftali Herz Cerf Brandeis was living near Metz and confirms this is the same family [note the author of this text was Naftali Herz Cerf Brandeis' uncle].

We know Naftali Herz Cerf Brandeis had a son named Jacob Brandeis (1732 marriage record). And there is no documentation of any of Jacob Brandeis' children getting married in France, which implies they moved elsewhere in Europe. It thus appears likely that this is the correct line of descent for R' Yitzchak Isaac Weisman.