Q. Shalom Aleichem Harav. What should one do if they forgot to lean for the 3rd cup (at the Pesach seder)?

A. Rema (O.H. 472: 7) rules that if one did not recline on the third or the fourth cup, one should not repeat and drink another while leaning, since this could qualify as adding to the four cups. In that case we should better rely on the opinion of the Rabiah, who maintains that no haseiva is required in our days when we usually do not recline at all during meals. (See also Igrois Moishe O.H. 3: 67).

Rabbi A. Bartfeld as advised by Horav Shlomo Miller Shlit’a