There is a custom that some people observe to place twelve Hallot on the table on Friday night. Although most people have the practice to use just two Hallot, according to Kabbalistic teaching twelve Hallot should be used. This custom is mentioned by the Ben Ish Hai (Rav Yosef Haim of Baghdad, 1833-1909), and this was the practice in Halab (Aleppo, Syria). The twelve Hallot were arranged in a series of "Segol" shapes (one Halla over two adjacent Hallot). The Ben Ish Hai, in the "Sod Yesharim" section appended to the first volume of Rab Pe’alim (Siman 13), writes that those who follow this custom should do so on Shabbat during Pesah, as well, and they should use twelve Masot at the table in honor of Shabbat.
The accepted custom is not to recite Shalom Alechem when the first night of Pesah falls on Shabbat. We proceed immediately to Kadesh, without reciting Shalom Alechem, even though it is Shabbat. This, too, is mentioned by the Ben Ish Hai in "Sod Yesharim." Generally, on Friday night we are joined by angels in order to bring upon us the special sanctity of Shabbat. On Pesah, however, the Almighty Himself comes and joins us, as we read in the Haggadah, "I and not an angel, I and not a Saraph…" We therefore do not need angels on Pesah to help us experience the Kedusha of Shabbat, and for this reason we do not recite Shalom Alechem.
It is customary for parents to give their children a blessing after Kiddush on Friday night. This custom should be observed when the night of Pesah falls on Friday night, and all the more so, as blessings given on the night of Pesah are especially meaningful and laden with spiritual power as a result of the sanctity of the occasion.
Those who have the custom to smell Besamim (fragrant spices) on Friday night should do so when Pesah falls on Friday night, assuming, of course, that the spices are Kosher for Pesah. The custom in our community is to smell Hadas branches, which are obviously permissible on Pesah, and thus we should observe this practice on Pesah, as well.
Summary: Those who observe the custom to use twelve Hallot on Friday night should use twelve Masot when the night of Pesah falls on Friday night. The custom to bless one’s children, and to smell Hadasim, should also be observed on Pesah night that falls on Friday night, just as on every other Friday night. However, Shalom Alechem is not recited on Pesah night.
