During the seven days following the wedding, festive meals are held in honor of the bride and groom, and at the end of Birkat haMazon the Sheba Berakhot, the seven blessings, are recited. But not at every meal. There are three conditions.
THE THREE CONDITIONS
1. Minyan. Ten adult men must be present. The groom counts among them.
2. Bet hatanim. The meal should take place at the couple’s residence. There are differences on this point: in several Sephardic communities in the diaspora the Sheba Berakhot are recited whether the meal is held at the couple’s home or elsewhere. Consult the rabbi of your community. The Ashkenazic custom also permits reciting them even when the meal is not held at the couple’s residence.
3. Panim hadashot. At least two “new” guests must be present: people who did not attend the wedding or the previous Sheba Berakhot. The Ashkenazic custom is satisfied with one new guest rather than two. The conditions of panim hadashot and of minyan are the same in all Sephardic communities.
WHEN A CONDITION IS MISSING
If one of these conditions is not met, and there are at least three adult men taking part in a formal meal, only the last blessing is recited: Asher bara.
HOW THEY ARE RECITED
When the Sheba Berakhot are said, the custom is to use two cups of wine. Birkat haMazon is recited over the first cup, and when the Sheba Berakhot are finished, the one who led Birkat haMazon himself says Bore peri hagefen. The other six blessings are said over the second cup. Once the last blessing has been recited, the wine from both cups is mixed and given to the bride and groom to drink.
When only Asher bara is recited, the custom is to say Bore peri hagefen first and then Asher bara.
Rabbi Yosef Bitton