I try my luck again:
I am trying to find out who his grandfather was (on his mother's side). The information I received from the Horowitz family says that he was the grandson of Hagaon who wrote the book: gaon zvi. The problem in the Horowitz family was a number of people who wrote a book by that name,
And I could not find which one was his grandfather (and my great-grandfather too).
I would be very grateful for any help