My guess is that my greatgrandfather, R' Yacov Gedalya Schechter, died early 20th cent. in Jerusalem, was a Vizhnitz Chosid. Two hints: He was buried (to the best of my knowledge) in the Vizhnitz section on Har Hazeitim.
Secondly: He held a minhag of not saying "Harachamin" in benching on Shabbat. (I know that the Gr"a also didn't say the, but I discovered that one of the admori"m of Vizhnitz also held that minhag).

Today many of his chassidic descendants are Breslev, including Rabbi Yacov Meir Schechter of Jerusalem.

How can I confirm, preferably on-line, that my ancestor was actually a Vizhnitzer chosid?

Shabbat Shalom and Chag Shavuot Sameach