Our minhag, which is in accordance with the Shulchan Aruch, has the filling of the second cup after Ha Lachma Anya before Mah Nishtana. However, the Rambam puts the filling of the second cup before Ha Lachma Anya. What is the basis of this machlokes? The answer is that it is a function of yet another machlokes. We have Yachatz right after Karpas. The Rambam, though, puts Yachatz all the way after Maggid and the drinking of the second cup, right before Motzi Matza. Why do we break the matzah before Maggid? It’s as the Mishna Brurah brings down from the Gemara, to fulfill both drashos of “lechem oni” – lechem sheh’onin alav devarim harbei – bread over which many words are said (meaning, maggid), and oni mi’lashon ani – poor – and the way of a poor man is to eat a prusah, a broken piece. Our minhag, then, is to make the matzah into full-fledged lechem oni before we begin Maggid. That being the case, the paragraph of Ha Lachma Anya, according to our minhag, is an explanation for the action of Yachatz. Why did we just break the matzah? Because it needs to be lechem oni. So Ha Lachma Anya is not part of Maggid; it is just an explanation for Yachatz which is a preparation for Maggid. That is why we only pour the second cup after Ha Lachma Anya. We recite Maggid over the second cup. Since Ha Lachma Anya, according to our minhag, is not part of Maggid, we wait until after it to pour the second cup. According to the Rambam, though, that Yachatz only comes immediately preceding Motzi Matzah, it is obviously not possible to understand Ha Lachma Anya as an explanation of Yachatz. Therefore, it must be that according to the Rambam, Ha Lachma Anya is in fact a part of Maggid. Therefore, the cup over which Maggid is said must be in place before we begin Ha Lachma Anya. That is why the Rambam puts the pouring of the second cup before Ha Lachma Anya.
[Rav Moshe Twersky ztz"l Hy"d]
