Gender: boy
I found living at Pfeffer 13 flat 14 Leon Grynstein born 1900 and he also had STALAG I (not sure if it's an address) and I found him as Leon Greunstein, and i found Masza Grynstein born 1903 and Frymeta born 1887 and her note says (crossed out).
I found Tadeusz Grünstein born 13 Apr 1927 in the [Mauthausen inmate list of Jews born in Łódź] and he was born in Lodz, Poland. His prisoner # 133682 he arrived in Mauthausen on 26 Feb 1945 from Sachsenhausen. I'm guessing this is the same Tadeusz from stage 1.
I couldn't find anymore information on Tadeusz.