Q. We have a minhag that we do a Seuda Leiluy Nishmas Reb Yonasan Ben Uziel together with other families of friends on Tu Bav since Seforim say that it is a Segula for finding the right Shiduchim for our children. This year since Tu Beav is Erev Shabbos, can the Seuda be done on Friday night?
A. Indeed as the Talmud (end of Taanis) mentions, one of the reasons why Tu B'av was considered one of the two greatest Yomim Tovim in our tradition is due to the fact that Shiduchim were obtained on that day
There is a minhag for some to make a Seuda during Tu Beav (Karlin Beis Aharon and others. See Nitei Gavriel 98: 7, and question above).
The Arizal also writes that Tu B’Av is a Segula day of to merit finding a Shiduch. Many also visit the Kever of the Tanna Reb Yonasan Ben Uziel in Amuka and daven for finding soon the correct mate.
It stands to reason since you have to prepare for the Shabbos Seuda on Friday, it is also considered a Tu B'av Seuda.
Horav Yaakov Hirschman's Shlit'a and Horav Aharon Miller's Shlit'a opinion is similar.
Rabbi A. Bartfeld as revised by Horav Dovid Pam, Horav Aharon Miller and Horav Chanoch Ehrentreu Shlit'a.