(Today’s Halacha was presented in Hebrew by HaGaon Rav Shemuel Pinhasi Shelit"a of Jerusalem)
On all Yamim Tobim, we recite the Beracha of "Shehehiyanu" over the day itself. The very occasion of the Yom Tob requires us to recite "Shehehiyanu." Additionally, there are special Misvot which we perform on the holiday which also require us to recite "Shehehiyanu." Thus, for example, on the night of Rosh Hashanah, we recite "Shehehiyanu" at Kiddush, but then the following morning we recite the Beracha again over the Misva of Shofar. One Beracha is recited over the occasion itself, and it is recited again over the Misva that applies on this day. Likewise, on the first night of Sukkot, we recite the Beracha of "Shehehiyanu" at Kiddush, and we recite it again the next day when we take the Arba Minim.
On Pesah, too, we recite "Shehehiyanu" at Kiddush at the Seder for the occasion of the Yom Tob. However, on this night we also perform several special Misvot – Masa, Marror, the four cups of wine, and so on. We do not recite "Shehehiyanu" over these Misvot, because we have in mind that the Beracha recited at Kiddush covers all the Misvot of the night. It is therefore imperative that all the Misvot – the Masa, the Marror and the wine – be placed on the table at the time of Kiddush, so that the "Shehehiyanu" recited at Kiddush will apply to them, as well. If these items are not on the table for Kiddush, one runs into a Halachic question concerning the recitation of the Beracha, and one must therefore ensure to remind his wife to set the Masa, Marror and wine for the four cups on the table for Kiddush. This is the ruling of Rav Shlomo Zalman Auerbach (Israel, 1910-1995), Hacham Ovadia Yosef, and others.
There is a debate among the authorities (between Rav Shalom Mesas and Hacham Ovadia Yosef) as to whether one who forgets to recite Ya’ale Ve’yabo in Birkat Ha’mazon on Yom Tob must repeat Birkat Ha’mazon. However, according to all opinions, one who forgets to recite Ya’ale Ve’yabo in Birkat Ha’mazon at the Seder must repeat Birkat Ha’mazon. Since there is an obligation to eat Masa on Pesah night, one must repeat Birkat Ha’mazon if he forgot to recite Ya’ale Ve’yabo. This applies to both and women, because women, too, are included in the Torah obligation of Masa on Pesah night, as anyone included in the prohibition of Hametz is included in the obligation of Masa.
During Hol Ha’mo’ed, however, one who forget to recite Ya’ale Ve’yabo in Birkat Ha’mazon does not repeat Birkat Ha’mazon. Even though one must repeat the Amida on Hol Ha’mo’ed if he forgets Ya’ale Ve’yabo, one does not repeat Birkat Ha’mazon. Even on Yom Tob day, according to the accepted Halacha, one does not repeat Birkat Ha’mazon if he forgot to recite Ya’aleh Ve’yabo, due to the difference of opinion regarding this issue.
As we know, the Afikoman must be eaten at the Seder before Hasot. It is important not to forget to eat the Afikoman before Birkat Ha’mazon. If one remembered after reciting Birkat Ha’mazon that he forgot to eat the Afikoman, then he must wash Netilat Yadayim, eat the Afikoman and then recite Birkat Ha’mazon again. If he will be eating two Ke’zetim for the Afikoman (which is the preferred amount), then he recites the Beracha of "Al Netilat Yadayim" when washing his hands. But if he will be eating only one Ke’zayit (which often happens, as many people find it difficult to eat large quantities of Masa after the meal), then he should not recite the Beracha of "Al Netilat Yadayim." In order to avoid this issue, one should make an effort to ensure not to forget to eat the Afikoman before Birkat Ha’mazon.
Summary: One must ensure that all the Misvot of the Seder, such as the Masa and Marror, are on the table for Kiddush. One who forgets to recite Ya’ale Ve’yabo in Birkat Ha’mazon at the Seder must repeat Birkat Ha’mazon; this applies to both men and women. But one who forgets to recite Ya’ale Ve’yabo in Birkat Ha’mazon at other times during Pesah does not repeat Birkat Ha’mazon. One who forgot to eat the Afikoman before Birkat Ha’mazon must wash Netilat Yadayim, eat Afikoman and recite Birkat Ha’mazon.
