Gamshey (Yehoshua, Joshua) Katzenelenbeigen (Katzenelenbogen)

We got opinion of Mr. Neil Rosenstein:

IN MY opinion it's more likely (BUT I HAVE NO PROOF - ONLY CIRCUMSTANTIAL EVIDENCE BASED ON GIVEN NAMES, POSSIBLE DATES PLUS WHAT I ADD BELOW) that YOUR line traces back to the two brothers David 1805 and Avraham 1808 AND that their father could have been a son of Dov Berish that you mentioned. Support comes from
1. DovBerish went from Galicia to Poritzk/Poryck (= Vladimir-Volinskiy/ Pavlovka) to published Mayim Yechezkel written by his ancestor Yechezkel of Hamburg there where they had a number of publishing presses, some also early Chassidic presses (the founder Baal Shem Tov died in 1760).
2. DovBerish's father Joel ben David of Keidaniai.
3. DovBerish's brother was Rav Avraham of Brest who put Levi Yitzchak of Berdichev (1740–1809) into Cherem (ban) & Levi Yitzchak was close with the Baal Tanya.
4. DovBerish mentions in Mayim Yechezkel that he had a son-in-law called Yehoshua Segal which means he was a levite son of Shmuel Segal and both were descendants of R. Eleazar, ABD Dubno (see also in my books).
5. In case female names help DovBerish's wife was Yenta Mintzi.
6. Note that both YOUR David and Avraham had sons DovBerish who could have been named after DovBerish ben Joel!
7. As was often the case, when children "converted" to Chasssidism their parents cut off ties (even sat shiva) AND these children were not longer recorded as part of the family!!

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of course it is possible that DovBerish of the Poritzk book could have had a son Yehoshua and son-in-law Yehoshua. Maybe, if he only had a son-in-law Yehoshua, then your line would be levite (the family adopting the maternal K. lineage - very commonly done).

У нас нет ни единой записи о самом Гамшее Каценеленбейгине.

Все, что мы достоверно знаем, это записи о Абраме Гамшеевиче из Любавичей и Бабиновецком мещанине Давиде Гамшеевиче. В то время (с 1784 по 1857) Любавичи относились к Бабиновецкому уезду, поэтому, наиболее вероятно, что Довид Гамшеевич жил именно в Любавичах.

Разумно предположить, что Абрам и Давид Гамшеевичи являются братьями. Данное предположение основано на следующих доводах:

1) Общее место жительства.

2) Оба имеют сыновей с именем Берка. Берка Абрамович и Берка Давидович имеют детей с именами Гамшей/Авсей и Мендель.

3) Образец аутосомной ДНК потомка Абрама Гамшеевича Анны Каценеленбоген (единственный имеющийся тест его потомка) имеет совпадения с образцами потомков Давида Гамшеевича.