I am sorry that I had to write in English but I would easier explain what I attend to do.
I have read some of Vadim's texts about Vrančić family and his own connections to them as Verenicz and I would like to write something what I know since I am for a long time amateur geneaologist specialized for ex-Yugoslavia geneaology.
First person I would like to say something about is
Đuraš Vrančić or
Đuraš Ilijić.He was buried in the Church of Saint Michael on Prevlaka (Boka Kotorska bay) with the inscription
in Emperor's Stefan's name a fearsome knight. Emperor Stefan is serbian Emperor Stephan Dusan, whose knight was Đuraš Ilijić. Sister of Emperor Dušan, Helen held in that time city of Skradin and Šibenik in Croatia. Stefan Dušan sent her military help consisted of serbian knights led by Đuraš Ilijić and his brothers, sons and nephews to protect her from Hungarians. They kept the city till 1356. and after that they deliver it to Venetians. That's how probably Šibenik noble family Vrančić appeared in the city.
The most known early ancestor of Vrančićs was Ilija, probably the father of Đuraš, who was head (title čelnik) of the region of Upper Zeta during the reign of Stefan Dečanski, serbian king and the father of serbian Emperor Stefan Dusan. Since the Balšić family come in to power in Zeta after death of Stephan Dusan, Vrančićs were supressed to their original homeland- eastern side of Bokokotorska bay, Prevlaka, Grbalj to Budva. As we see Đuraš Vrančić was burried on Prevlaka.
Son of Đuraš Vrančić was Crnoje founder of the house of Crnojević. Interestingly, both Crnojević and Vrančić meaning 'black' in serbian. Son of Crnoje,
Radič ruled with mentioned region of Vrančićs and his fool title in documents were
Lord of the Zeta and Budva and the other parts of Serbia. By the end of 14th century Radič succeeded to defeat Balšićs and take full control over Zeta. His sons ruled Zeta till the Otoman conquest in 1499.
I was writing before about serbian clans. One clan I studied very thoroughly recently is clan Nikšići. Nikšići is one of well known Herzegovian serbian clans from the town of Nikšić. Actually city of Nikšić, in old Herzegovina (today Montenegro) is named by them Nikšić in 14th century when they settled there and earlier name of the city was Onogošt. Nikšićs were descendandts of duke Nikša (short from Nicholas) who lead their clan in migration from the bay of Bokokotorska, Grbalj and Prevlaka (same regions as Vrančićs) to Herzegovina in the region of Onogost. According to oral legend Nikša was a son of ban Ilijan from Grbalj. And ban (title) Ilijan was according to legend some cousin of Nemanjic dynasty.
So, we have one Ilija(n) from the same period, same region and with same connections with Nemanjics in two different stories. All what we can conclude is that Ilija father of Đuraš Ilijić, founder of Vrančićs and Crnojević and Ilijan father of Nikša, founder of Nikšić clan, is the same person from 14th century- Head or duke of Zeta Ilija(n), connected with Nemanjic dynasty, as legend said through marriage with one of Nemanjics daughters.
Patron saint and slava of Nikšić clan is st. Luke, the main orthodox cathedral in the city of Kotor, and in the city of Nikšić is dedicated to st. Luke.
Serbian family Klaich (Kljajić) from Krajina region in Croatia belongs to Nikšić clan, they celebrate st. Luke and know that descended from duke Nikša. There is one whole clan with different surnames from those Nikšićs in Croatia and even Slovenia which are orthodox Serbs and celebrate st. Luke. Šević, Opačić, Bilbija, Drašković etc.
One individual from this Klaich family made a test and his results was I2a1b1 Dinaric North.
Closest haplotype to him was Vranješević (same etimology of name as Vrančić 'black'), Serbian from Modriča region in Bosnia. All orthodox family in that region descend from Herzegovina region. So I am quite sure that Vranješević also belong to Nikšić clan.
After uprisal and disaster against Turks in the late 16th century which were led by Grdan Nikšić, great part of Nikšić clan and their smaller part Trebjesani were resettled. Most of them fled to Russia, one part ended in Krajina region in Croatia and Slovenia and smaller part stayed in Herzegovina.
Since Nikšićs have Dinaric North haplotype it was quite strange for me because 80% of serbian Dinarics are South. But I think that the place of their origin (Eastern side of Bokakotorska bay, Grbalj, Budva) explain that unusuality. According to historical sources, old Serbs were not settled in the region of Duklja, later Zeta where the original region of Nikšićs and Vrančićs is. Porfirogenitus said that Slavs settled Duklja too but he doesn't mention what tribe. I suppose that ban or head Ilijan was descedant of one of Slavic tribal chiftains in early mediaval Duklja. Duklja very early in 10th century became part of Serbia and was its part till Ottoman conquest in 15th century. Serbian kings probably leave one family of local aristocracy (tribal chieftains) and make family connections with them. So, Vrančićs, Crnojević, Nikšićs are descedants of those.
One of russian generals from 18th century is from Nikšić clan
http://ru.wikipedia.org/wiki/Шевич,_Иван_Егорович
And also serbian tennis player Novak Djokovic is from Nikšić clan.