The only other Pikholz we knew who were old enough to be Izak Fischel's father are Berl (~1789-1877) and Leib (~1780-1844). The family all lived in Skalat, not far from Tarnopol in east Galicia.
I had done extensive work on the large family of one Mordecai Pikholz (~1805-1864) and using DNA, I had come to the conclusion - unproven - that he and Izak Fischel were brothers. I knew that Mordecai had daughters named Chana Chaje, Enie and Devorah and sons Chaim Yaakov, Shimon, Szulim and Aryeh Leib and I am in contact with some descendants of all of them but Enie.
Part of the evidence here was the perfectly matching Y-DNA of Dalia Kaplan's nephew and me, Dalia being a great-granddaughter of Mordecai's son Chaim Yaakov. The rest of the evidence is laid out in a two-part blog post here and here.
There was also a Mechel Pikholz (b. ~1833), son of Mordecai, who lived in Podolia, and really looked like he fit as a son of our Mordecai. Mechel is usually a nickname for Jachiel and that name showed up enough in the families to make Jachiel a candidate for the name of Mordecai and Izak Fischel's father.
Due to my conservative practices, I considered all this to be speculation and did not record it in my database, except in the comments.
This week began with an email from the inimitable Lara Diamond who had found a Pigholtz record that was not in the Ukraine database at JewishGen. This database includes Podolia and I had turned my attention to it recently. Lara's find is the second record on this page.
I will take a deep dive into some of the newly available records - I am behind on that! - and well see if anything else comes up. For real proof that Zvi is my third great-grandfather, I am relying more on luck than on planning.