Randy Schoenberg Below is a synopsis of the tradition that The Horowitz Family Association follows. However, Private User might be able to direct you to other sources.
http://www.shlomo.horwitzfam.org/in_the_beginning.htm
According to ancient tradition passing from generation to generation, the Horowitz family originated from a dynasty of well-known Spanish and French rabbis and scholars:
R. Yitzhak Ha-Levi of Gerona, the son of R. Pinchas Ha-Levi, the brother of famous HaROeH (R. Aharon Ha-Levi) of Barcelona, the son of R. Yosef Ha-Levi, the son of R. Banbaneshti Ha-Levi, the son of R. Yosef Ha-Levi, the son of R. Zerakhyah Ha-Levi, the author of "Ha-Maor", the son of R. Yitzhak Ha-Levi of Gerona, the son of R. Zerakhyah Ha-Levi, the son of R. Shem-Tov Ha-Levi, whose roots, in turn, can be traced back to the prophet Shmuel.
ie. Yeshaya HaLevi Horowitz - The first Horowitz is related to Zerachyah Reuben Ha'Levi ben Shemtov Halevi: http://geni.com/KmnHc
This Horowitz family legend can be found in an internet version of a book written and published by Shlomo Gurevich which is now available in English as well as in Russian language: "Gurevich, Gurovich, Gurvich, Gorvich, Gurvitz, Horowitz and others. History of A Great Family" (Haifa, 1999, ISBN 965-222-971-7)
Randy Schoenberg It is an excellent question. I would imagine the Horowitz Association members have done the most extensive research available on this topic, and perhaps if contacted they might be able to provide the first source for this legend.
Association Contact Information:
The Horowitz Families Association
The Bible Museum
16 Rothschild Boulevard, Tel Aviv 66881, Israel
Tel: 03-5166393/5177760 Fax: 03-5107661
E-mail: horowitzassociation@yahoo.com
Webmaster: shl2gur@hotmail.com
or, you maybe try contacting some members directly,
http://www.shlomo.horwitzfam.org/members.htm
Moshe shaltiel Gracian, with whom I am in frequent contact, as well as Dr Arthur Menton and the Dayan family of Aleppo are the nucleus of early claims.
Moshe reconstructed the Shealtiel exilarch migration into Catalonia, using extant texts found in Toledo and Barcelona.
Dr Menton reconstructed the Charlap Family tree from a different collection of texts - this is how I became involved...to research the origins of Portuguese Jewry and its connection to the exilarchs of Qairouan and Bavli. Mission accomplished.
Mitch Dayan's family text is an authoritative pedigree of the Aleppo Exilarchs. There are no challengers to this pedigree and the Y-DNA seems to authenticate it.
The Families who claim descent from Maharal of Prague do so via the little known son of Yehosef haNagid (Yehosef was killed in Granada in 1066); Aryeh was his son.
The Horowitz Family, of which there are many branches(Horwitz, Horowicz, etc) alternatively claim descent from Yehosef haNagid of Granada, and a catalonian Rabbi. The connection to Maharal of Prague is well known. The Connection to the Rabbi in Barcelona less so. It will require research through Moshe Shaltiel's documents of Catalonia to authenticate.
J
Everyone should read this new article by Rabbi Marmorstein.
http://www.avotaynuonline.com/2016/03/does-the-horowitz-family-from...