Written by Rabbis Eli Gersten, Yaakov Luban, and Moshe Zywica of the Orthodox Union
There is no perfect solution. Some poskim hold that Seudat Shelishit should be eaten after midday, and some poskim hold that bread must be eaten at Seudat Shelishit. It is not possible to satisfy both requirements for Seudat Shelishit (to eat bread and eat after chatzot) on erev Pesach.
Nonetheless, we try to fulfill the mitzvah of Seudat Shelishit as best as we can. First, we divide the morning meal into two parts. One should recite kiddush and Hamotzi, eat one course, and then bensch (recite the Grace After Meals). After a break of half an hour, we wash again, say Hamotzi, eat the rest of the meal and bensch once again. (The challah or egg matzo that is used for lechem mishneh should be consumed before the end of the fourth hour, the time when chametz can no longer be consumed). By doing this, we fulfill the mitzvah of Seudat Shelishit according to the poskim who allow the meal to be eaten in the morning.
In addition, it is best to eat fish, meat, or fruit in the afternoon, as some say these foods are sufficient to fulfill the mitzvah of Seudat Shelishit even without eating bread at the meal. However, one should not overeat, so that the matzo at the Seder will be consumed with an appetite.