Let's start from the beginning...

Her mother was Danica Rosić and her father was Vojin Abramović. (http://archive.is/wpDtj#selection-1351.212-1351.275))

So I do some digging and I find this...

29.08. 1880. Rođen u Pljevljima Petar Đ. Rosić Varnava

Google translated:

UROŠ (1885 - 1937) he was a trader with his brother Alex. He was married with Milica Vojinovic from Uzice with whom he had four children: Danica Day Abramovic graduate. history.

(http://archive.is/C39LC#selection-963.0-965.171))

So Danica Rosić, Marina Abramovic's mother was his daughter...

Don't believe me? Check out what it says on Wikipedia...

Varnava, Serbian Patriarch

He was the great-uncle of performance artist Marina Abramović.

Varnava Rosić (Serbian Cyrillic: Варнава Росић) was the Patriarch of the Serbian Orthodox Church between 1930 and 1937.[1] He was born Petar Rosić in Pljevlja, belonging at that time to the Ottoman Empire, on August 29, 1880.

(http://archive.is/YPzcy#selection-681.0-685.1))

So they I do some more searches and I find his mention in 'Rasputin: The Biography'...

Slight and short with a high-pitched voice, Vamava, it was rumoured, liked to wear women's clothing,throw wild parties in the monastery, and take boys to his bed. Father Georgy Shavelsky, the last protopresbyter of the Imperial Russian army and navy, characterized Vamava in a letter to Father Vostokov as a cunning and nasty figure of unhealthy ambition. He said Vamava was the confessor to "that Mason Count Witte, and is himself an atheist -Mason." Shavelsky even claimed Varnava had sexually abused and then murdered a beautiful young altar boy at Kolomna, his body discovered lodged under a mill wheel.

Here is the kicker though...

Vamava and Rasputin met in one of the capital's salons, and if they did not become friends, the two men of similar backgrounds apparently realized they could be of use to each other: Rasputin could help advance Varnava's career, Vamava could defend Rasputin against attacks from within the ranks of the church.

(https://books.google.com/books?id=npKqDAAAQBAJ&pg=PP208&lpg=PP208&dq=Varnava+mason&source=bl&ots=OVSuRnrREm&sig=4xq-jUE8eAf131wUfKpEFIkjZlM&hl=en&sa=X&ved=0ahUKEwivpdDSu-fQAhXFWxoKHYISBygQ6AEIGjAA#v=onepage&q=Varnava%20mason&f=false))

If you haven't heard of Rigori Yefimovich Rasputin check this documentary:

Most Evil Men In History - Rasputin (https://www.youtube.com/watch?v=8Y-CL7msZDk))

More info though not personally verified through other sources. Maybe someone can help with that...

Her maternal uncle was the powerful Varnava Rosić– Patriarch of the Serbian Orthodox Church between 1930 and 1937. His body is interned at the Temple of Saint Sava in Belgrade. He believed that Hitler’s policy toward Jews and lesser races served all mankind. His last act was to oppose a Vatican Concordat to control the Orthodox Church. Knights assassinated him with poison before the final vote.

The (Orthodox) Temple of Saint Sava in Belgrade, Serbia is the largest Orthodox Church currently in use. The church is dedicated to St. Sava, founder of the Serbian church and an important figure in medieval Serbia. From its location, the temple dominates Belgrade’s skyline and is perhaps the most monumental building in the city.

Saint Sava (1174 – 1236), was known as The [Luciferian] Enlightener. He was a Serbian prince and Orthodox monk, the first Archbishop of the autocephalous Serbian Church. He was a prince of the House of Nemanjić descended from a Cabet Vukanovic Dynasty (1106- 1166) line of Hugh Cabet. I believe that this is Marina’s secret maternal East European Merovingian BLOODLINE, the House of Nemanjić.

(http://archive.is/ZWPwP))

Though I haven't found a direct link I believe that the name Rosić links to the Rosicrucianism secret socitey...

Rosicrucianism is a philosophical secret society said to have been founded in late medieval Germany by Christian Rosenkreuz. It holds a doctrine or theology "built on esoteric truths of the ancient past", which, "concealed from the average man, provide insight into nature, the physical universe and the spiritual realm." Rosicrucianism is symbolized by the Rosy Cross or Rose Cross. (http://archive.is/5XW0G#selection-1289.0-1289.383))

(http://www.artnet.com/artists/marina-abramovi%C4%87/artist-portrait-with-a-rose-a-UFCh9RtcaGiFZmmJxBYKcg2?))

Is this for real? How deep does the rabbit hole go?!?!

EDIT: Added more info on Varnava Rosić