Question: Carloman abdicated Italy to the great-grandson of who?

Context paragraphs:
Prince Hermann Friedrich of Leiningen: Prince Hermann Friedrich of Leiningen (born 16 April 1963) is the younger son of Prince Karl of Leiningen and his wife Princess Marie Louise of Bulgaria.  Hermann was born in Toronto, Ontario, as Hermann Friedrich Fernando Roland.  Through his mother, Hermann is a grandson of King Boris III of Bulgaria, a great-grandson of King Victor Emmanuel III of Italy and -great-great-grandson of King Nicholas of Montenegro.  Through his father, he is a great-great-great grandson of Queen Victoria (thus in the line of succession to the British throne), as well as Tsar Alexander II of Russia.  According to Marlene Eilers, Hermann of Leiningen belongs to the Eastern Orthodox Church.  His paternal grandmother was Grand Duchess Maria Kirillovna Romanova of Russia and his maternal grandmother was Princess Giovanna of Savoia, daughter of King Victor Emmanuel III of Italy.

Frankish Papacy: From 756 to 857, the papacy shifted from the orbit of the Byzantine Empire to that of the kings of the Franks.  Pepin the Short (ruled 751–768), Charlemagne (r. 768–814) (co-ruler with his brother Carloman I until 771), and Louis the Pious (r. 814-840) had considerable influence in the selection and administration of popes.  The "Donation of Pepin" (756) ratified a new period of papal rule in central Italy, which became known as the Papal States.

Pepin the Hunchback: Pepin, or Pippin, the Hunchback (French: Pépin le Bossu, German: Pippin der Buckelige; c. 769 – 811) was the eldest son of Charlemagne.  Born to the Frankish noblewoman Himiltrude, Pepin probably developed kyphosis after birth, leading early medieval historians to give him the epithet "hunchback".  He lived with his father's court even after Charlemagne dismissed his mother and took another wife, Hildegard.  Around 781, Pepin's half brother Carloman was rechristened as "Pepin of Italy"—a step that may have signaled Charlemagne's decision to disinherit the elder Pepin, for a variety of possible reasons.  In 792, Pepin the Hunchback revolted against his father with a group of leading Frankish nobles, but the plot was discovered and put down before the conspiracy could put it into action.  Charlemagne commuted Pepin's death sentence, having him tonsured and exiled to the monastery of Prüm instead.  Since his death in 811, Pepin has been the subject of numerous works of historical fiction.

Carloman of Bavaria: Carloman (German: "Karlmann" , Latin: "Karlomannus" ; c. 830 – 22 March 880), was a Frankish king of the Carolingian dynasty.  He was the eldest son of Louis the German, king of East Francia, and Hemma, daughter of a Bavarian count.  His father appointed him margrave of Pannonia in 856, and upon his father's death in 876 he became King of Bavaria.  He was appointed by King Louis II of Italy as his successor, but the Kingdom of Italy was taken by his uncle Charles the Bald in 875.  Carloman only conquered it in 877.  In 879 he was incapacitated, perhaps by a stroke, and abdicated Bavaria to Louis the Younger and Italy to Charles the Fat.

Louis the Younger: Louis the Younger (830/835 – 20 January 882), sometimes Louis III, was the second eldest of the three sons of Louis II the German and Emma.  He succeeded his father as the King of Saxony on 28 August 876 and his elder brother Carloman as King of Bavaria from 880 to 882.  He died in 882 and was succeeded in all his territories, which encompassed most of East Francia, by his younger brother, Charles the Fat, already King of Italy and Emperor.

1973 Afghan coup d'état: The 1973 Afghan coup d'etat took place on July 17, 1973 in Kabul, Afghanistan when forces led by Mohammed Daoud Khan overthrew the monarchy in a somewhat bloodless coup.  At the time King Mohammed Zahir Shah was abroad receiving eye surgery and treatment for low back pain in Ischia, Italy.  Daoud Khan was assisted by leftist Afghan Army officers and civil servants from the Parcham faction of the PDPA, including Afghan Air Force colonel Abdul Qadir.  Eight officers were killed.  King Zahir Shah decided not to retaliate and he formally abdicated on August 24, remaining in Italy in exile.  More than two centuries of royal rule (since the founding of the Durrani Empire in 1747) ended.

Baron Vestey: Baron Vestey, of Kingswood in the County of Surrey, is a title in the Peerage of the United Kingdom.  It was created in 1922 for the shipping magnate Sir William Vestey, 1st Baronet.  He was the co-founder of the Blue Star Line.  Vestey had already been created a baronet, of Bessémer House in the Metropolitan Borough of Camberwell, in 1913.  s of 2010 the titles are held by his great-grandson, the third Baron, who succeeded his grandfather in 1954.  He is the eldest son of the Hon. William Vestey (died 1944) (who was killed in action in Italy during the Second World War), only son of the second Baron.  Lord Vestey has served as Master of the Horse since 1999.

Baron Vivian: Baron Vivian, of Glynn and of Truro in the County of Cornwall, is a title in the Peerage of the United Kingdom and held by a branch of the Vivian family.  It was created in 1841 for the soldier Sir Hussey Vivian, 1st Baronet.  He had already been created a baronet, of Truro in the County of Cornwall, in 1828.  His eldest legitimate son, the second Baron, represented Bodmin in the House of Commons and served as Lord Lieutenant of Cornwall.  His son, the third Baron, served as British Ambassador to Italy from 1891 to 1893.  The latter's great-grandson, the sixth Baron, was a soldier and a Conservative member of the House of Lords.  Lord Vivian was one of the ninety elected hereditary peers that were allowed to remain in the House of Lords after the passing of the House of Lords Act 1999.  As of 2014 the titles are held by his only son, the seventh Baron, who succeeded in 2004.

Charles the Fat: Charles III (13 June 839 – 13 January 888), also known as Charles the Fat, was the Carolingian Emperor from 881 to 888.  The youngest son of Louis the German and Hemma, Charles was a great-grandson of Charlemagne.  He was the second-last emperor of the Carolingian dynasty and the last to rule, briefly, over a re-united Frankish empire.

Louis Victor, Prince of Carignano: Louis Victor of Savoy (25 September 1721 – 16 December 1778) headed a French cadet branch of the Italian dynasty which reigned over the Kingdom of Sardinia, being known as the Prince of Carignano from 1741 till his death.  Upon extinction of the senior line of the family, his great-grandson succeeded to the royal throne as King Charles Albert of Sardinia, while his great-great-grandson, Victor Emmanuel II, became King of Italy.

Supporting paragraphs: Carloman of Bavaria Charles the Fat
Answer: Charlemagne