His mothers father was R. Zalman Freidin who in turn was the son in law of R. Zalman Chaikin of Podobranka.

R. Levi Yitzchak Schneersohn was a grandson of the aforementioned R. Zalman Chaikin as well. He and R. YM’s mother were first cousins. His son, the Lubavitcher Rebbe and R. YM were second cousins.

You will need to point out which Rebbe you are reffering to (I think you are talking about Lubavitch but not 100 % Sure).

How were they related?

Interesting – they were cousins, born in the same small hamlet Podobranka deep in White Russia over 100 years ago, and endend up having kevorim on the other side of the world not to far from each other!

If you read the Toldos closely, they did not have much connection, having met here in America only one time. However, there is a letter from the Rebbe where he refers to Harav Shurkin z”l as ” hu ben iri umishpachti v’yorei Elokim bemes”. They say this is the only time the Rebbe wrote on someone “yorei Elokim bemes”…

Correction to to Directions to kever:
In Elmont cemetary, the kever is on Jericho Avenue, between Jackson Ave and Monroe Ave. (Best to stop in office for map.)

Corrections to 4 responses above:

His father-in-law was HaGaon HaRav Yaakov Kantorovich zt”l, which those that knew him (including his nephew HaGaon HaRav Moishe Feinstein zt”l) held of him as the Gaon HaDor. He was Rav of Timkavitch in Russia and at the end of his life, when the communist took over Russia, and all rabbonim’s lives were in danger, he and R’ Moishe were of the last Rabbonim to escape to America where HaRav Kantorovich bacame rav of Trenton, NJ. He authored Tzilusa DeShmaatsa on the Shev Shmaatsa, Chidushei HaGR”Y and other seforim.
He was originally buried in Trenton. Later on, with a specific psak from his nephew R’ Moishe, the kever was moved to the chelkas harabbonim in Beis Shemesh, E”Y.

Rav Avrohom Kantorovitch, mentioned above, was a son of Harav Yaakov and a brother-in-law of HaRav Shurkin. He was a shochet in Mexico who had a strong mesorah of nikkur which he passed down to younger butchers. Every year on both his mother’s yarhtzeit and his father’s yarhtzeit he would make a siyum mesechta, and he was mesayim sha”s. He was active in publishing his father’s seforim and wrote introductions t them.

HaGaon HaRav Y. M. Shurkin’s son, HaGaon R’ Michel shlit”a, is also a talmid of his father, HaGaon R’ Moishe, HaG’ R’ Leib Malin and HaG’ R’ Shmuel Charkover zt”l. He is a Rosh Yeshiva in Yeshivas Toras Moishe in ih”k Yerushalim t”v.