1) The sheva brachos cannot be recited unless at least one of the adult male participants is a panim chadashos. Panim chadashos, literally translated as “new face,” means that he was not present at the wedding dinner or at a previous sheva brachos for this couple. (S.A. E.H. 62:7) If there are no panim chadashos present, only the last of the sheva brachos, “asher bara” is recited.
2) According to the Rambam, two panim chadashos are required. This ruling was codified by the Ben Ish Chai (Shoftim 15). Many sefaradim follow this view.(See Yabia Omer 3 E.H. 11)
3) A person who attended the chuppah, but did not attend the wedding meal, still may be considered panim chadashos. (S.A. E.H. 62:7) Harav Moshe Stern zt”l writes that this is true even if he ate at a buffet before the chuppah. (Beer Moshe 2:119)
4) If he was present at the wedding meal or one of the sheva brachos meals, he can no longer be considered the panim chadashos, regardless of if he ate while he was there. (Hanisuin K’Hilchosom page 523) Therefore, if a person went to a wedding to wish mazal tov to the chosson and kallah, he can no longer serve as the panim chadashos, even if he did not eat at the wedding at all. (Yismach Lev vol. 3 page 24)
5) A woman cannot serve as the panim chadashos. (Pischei Teshuva 62:14)
6) A child cannot serve as the panim chadashos. (Pischei Teshuva ibid.)
7) The Shulchan Aruch (E.H. 62:8) writes that the panim chadashos is a person who is important enough that extra food is generally prepared in his honor and someone whose presence brings additional simcha. It seems that Rashi disagrees with this notion and feels that any person can serve as the panim chadashos. (See Shitah Mekubetzes Kesubos 7b) While this appears to be the prevalent custom, the Ben Ish Chai writes that it may be preferred to adhere to the strict ruling of the Shulchan Aruch. (See Ben Ish Chai Shoftim 16 and Hanisuin K’Hilchosom page 524) It is reported that the Chazon Ish also sought after panim chadashos who were very honorable. (Shalmei Simcha page 353)
8) The Sefer Hanisuin K’Hilchosom (page 525) cites an argument among the poskim as to whether a waiter at the restaurant where the sheva brachos are taking place can serve as the panim chadashos. For normative halacha, a rabbi should be consulted.
9) There are numerous opinions among the poskim as to whether the panim chadashos must partake of the meal. The Rama (62:7) rules that the panim chadashos does not need to eat at the sheva brachos meal. This ruling is codified by the Kitzur Shulchan Aruch. (149:5) The Sefer China V’Chisda (vol. 1 page 111) writes that the blessings are only recited if the panim chadashos eats something at the meal. This is also recorded in the Sefer Nesivei Am (vol. 2 page 8). Harav Avraham Farasko zt”l maintains that the panim chadashos must eat bread at the meal in order for the blessings to be recited. (Birech Es Avraham 71:32)
10) The panim chadashos must be present during the recitation of the sheva brachos. If the panim chadashos leaves before the blessings were recited, the poskim debate whether the blessings are recited. If the panim chadashos leaves in middle of the recitation of the blessings, the poskim disagree whether the remaining blessings are recited. For normative halacha, a rabbi should be consulted. (refer to Hanisuin K’Hilchosom page 526)
11) Days in which the panim chadashos are unnecessary- When sheva brachos take place at either one of the first two meals of Shabbos or Yom Tov, (see Bitzeil Hachochma 1:64) there is no need for an additional panim chadashos because the Shabbos and Yom Tov themselves are considered to be eminent “guests” who fulfill the role of panim chadashos. (Shulchan Aruch E.H. 62:8)
12) The poskim debate whether panim chadashos are required during the third Shabbos meal, known as seudas shlishis. The Shulchan Aruch (E.H. 62:5) rules that Panim Chadashos are required. The Rama M’Pano maintains that, kabbalistically the seudas shlishis is also considered a “guest” and panim chadashos are not required. (Pischei Teshuva 62:16)
Other poskim maintain that panim chadashos are required. However, if divrei Torah are delivered at the meal, the Torah is considered the “guest” of honor and the blessings are recited. (Shulchan Haezer 12:3) Preferably, the divrei Torah should be said by the chosson, (See Kitzur Shulchan Aruch 149:5) but if he cannot do so, any formal drashah of divrei Torah is sufficient. It should be noted that many poskim, including Harav Shlomo Zalman Auerbach zt”l, maintain that divrei Torah can only substitute the panim chadashos during the third meal on Shabbos. If there is no panim chadashos on a weekday, one cannot recite divrei Torah and then recite the blessings. (Shalmei Simcha 352)
Chanukah and Rosh Chodesh are not considered “guests” and panim chadashos are required.
13) The Sefer Yafeh Lalev writes that one does not require panim chadashos on Chol Hamoed. (Bitzeil Hachochma 2:1) Others, including Harav Ovadia Yosef zt”l, disagree. (Yabia Omer 3 O.C. 23)
14) Harav Ovadia Yosef zt”l rules that panim chadashos are required on Purim.