Rachmil Sendyk is the most similar name we found to Jerachmiel Sendok. Also, school #2 implies likely birthdates of students are between 1926 and 1931, and Rachmil Sendyk's birthdate is in 1928.
Looking up Sendyk's deportation date and comparing it to the list in the secondary sources, we found that the Sendyk's listed deportation date, April 15th, was not listed. However, seeing as all transports before May 15th were sent to Chelmno, we can infer that Sendyk was most likely sent there as well. We also found Hudes Sendyk, who we believe to be Rachmil's mother. She lives in the same address, deported the same day, and is 26 years old, a fitting age to have a child at the time. Including Rachmil's mother, we found Rachmil's younger brother, Kopel Sendyk, again living at the same address. Oddly he is not noted to be deported to Chelmno with the family. We also found who we believe to be Rachmil's sister, Rajzla Sendyk, living at the same address. Rajzla is listed twice in the USHMM list, with information left out from each. Rajzla is not noted as being deported to Chelmno in one, and is in the other. Szaja Sendyk was also found, who we believe to be Rachmil's younger brother. He is listed at the same address and deported the same day. Another Szaja Sendyk was found with a 1939 birthday, living at the same address of Rachmil. We believe him to be another brother of Rachmil. We found who we believe to be Rachmil's father, Zelig Sendyk, born in 1903, listed at the same address, and deported the same day. His father is also listed as a shoemaker.
Hudes Sendyk, Kopel Sendyk, Rajzla Sendyk, and Szaja Sendyk all lived at the same address (Altmarkt 10 6). Because Hudes Sendyk was born in 1902, we believe that she was the mother of Rachmil Sendyk. Also, we are confident that Rachmil, Kopel, Rajzla, and Szaja are siblings because of their same exact address and last name. Four of these five people (including Rachmil) have the same deportation date (April 15, 1942) to Chelmno. Because of this data we believe that the whole family (with the acception of Kopel because he did not have a deportation date) were all, unfortunately, executed together at Chelmno.
Zelig Sendyk is the last family member of Rachmil Sendyk that we have found. We believe that he is the wife of Hudes Sendyk and also the father of Rachmil and Rachmil's siblings. Besides having the same last name, Zelig lived at the same address (Alt Markt 10 6) and also four out of the five family members have the same deporation date to Chelmno (April 15, 1942
Based on the chart we found in the secondary sources, there was no deportation on April 15, 1942. We beleive that either the date of Rachmil's deportation is wrong, or that there were unlisted deportations on that day. Also, we found that "between January and May of 1942, more than 54,000 Lodz Jews were killed at Chelmno" (Secondary Sources) leading us to believe that he was most likely deported and killed at Chelmno.