Sheva Brachos Shailos

In the first perek of Kesuvos, there is a lengthy exposition on Sheva Brachos. What follows is some selected halachos regarding Sheva Brachos with a focus on the psakim of Rav Moshe Feinstein, zt”l. This article is not intended to issue practical rulings but to engender discussion.
The Rema (EH 62:6) writes that the seven days of celebration start at the conclusion of the Sheva Brachos recited at the chuppah. However, Rav Moshe ruled that if the chuppah took place close to sunset and the wedding meal did not start until after sunset, the first day of Sheva Brachos is the Hebrew calendar day on which the wedding meal took place.
Rav Elyashiv, zt”l, ruled that on the seventh day of Sheva Brachos, the Sheva Brachos should not be recited past sunset. Rav Elyashiv once related that the Klausenberger Rebbe invited him to the last Sheva Brachos meal being made in honor of his daughter (who married Rav Dov Weiss). He was to be honored with one of the Sheva Brachos. Rav Elyashiv politely declined, explaining that presumably the Sheva Brachos will be recited way after sunset in accordance with the chassidishe custom that halachic nighttime occurs 72 minutes after sunset. Rav Elyashiv felt that according to his custom, Sheva Brachos recited after sunset would be considered blessings in vain. The Klausenberger Rebbe assured him that the Sheva Brachos would conclude before sunset, and then Rav Elyashiv graciously accepted the invitation. However, Rav Moshe Feinstein, zt”l, ruled that (at least) in New York, Sheva Brachos may be recited on the 7th day until 40 minutes after sunset.