Gender: girl
I found two names that match the years 1921 and 1927 for B. Zajdenfeld.
The first name is Basia Zajdenfeld b. 22/12/1922 and she lived at Bier 24 and Korn 9 12. She was deported on TR 4/2 on 25/02/1942.
I also found another Basia Zajdenfeld b. 17/09/1925 and she lived at Blech 4 9.
Basia b. 1922 was the daughter of Chana Frajndla Zajdenfeld b. 1890 and she was the sibling/cousins of Chana b. 21/01/1918, Abram 14/10/1925, Perla b. 15/11/1929, Luba Frandla 29/12/1924, and Lewi Icchock b. 02/03/1927. They were all deported on TR 4/2 on 25/02/1942. According to the secondary resources the family were sent to Chelmno where they were killed in the gas vans.
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I couldn't find anyother information on Basia b. 1925.