From: Rabbi Moshe Sofer
To: Rabbi Zelig
The Chasam Sofer upholds the Rambam's ruling that when brothers died from circumcision, the surviving child should not be circumcised on time but must be circumcised once he grows stronger. He refutes the Noda BiYehudah Tinyana's view that such a child remains permanently uncircumcised, marshaling proofs from the Rashba, Rambam, and Talmudic sugyos. He also resolves the objection regarding pikuach nefesh and the majority principle, distinguishing between cases where a dangerous minority is established before us and ordinary circumcision where it is not.
Source: Shu"t Chasam Sofer YD §245