From: Rabbi Moshe Sofer
To: Unknown recipient
The Chasam Sofer addresses an apparent contradiction between Rashi in Arachin 3a (women cannot join zimun due to not reciting Bris) and Rashi in Berachos 20b (where the doubt about women's obligations stems from lacking nachalas ha'aretz, not Bris). He resolves this by showing that the Berachos sugya follows Rav's view that Bris is non-essential, while Rashi in Arachin reflects the normative halacha that Bris is essential.
Source: Shu"t Chasam Sofer OC §48