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.
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.