Date: 13 Adar I 5578
From: Rabbi Moshe Sofer
To: Rabbi Moshe Segal Margolies
The responsum addresses a ban established in 1793 between Ashkenazi and Sephardi communities, prohibiting members from praying in each other's synagogues, and seeks a dispensation for the Sephardim whose community has dwindled and prefer to pray in the Ashkenazi synagogue.
Source: Shu"t Chasam Sofer Collected §1