Theodora Angelina Palaiologina
Theodora Angelina Palaiologina( Greek: Θεοδώρα Άγγελίνα Παλαιολογίνα) was a Byzantine noblewoman and mother of the future Byzantine Emperor Michael VIII Palaiologos, the founder of the Palaiologan dynasty.
She was the daughter of the" despotes" Alexios Palaiologos and Irene Komnene Angelina, the daughter of Alexios III Angelos and Euphrosyne Doukaina Kamatera.
Robert Vadra
Robert Vadra is an Indian businessman, entrepreneur and the husband of Priyanka Gandhi.
He is the son -in- law of Sonia Gandhi and Rajiv Gandhi, and the brother- in- law of Rahul Gandhi.
Eudokia Angelina
Eudokia Angelina( or Eudocia Angelina)( around 1173 – died, or later) was the consort of Stefan the First- Crowned of Serbia from c. 1190 to c. 1200.
She later remarried, to Alexios V Doukas, who briefly ruled as Emperor of Byzantium in 1204.
She was a daughter of Alexios III Angelos and Euphrosyne Doukaina Kamatera.
Basil Doukas Kamateros
Basil Doukas
Kamateros was a Byzantine aristocrat and senior official.
Basil was the son of the official and theologian Andronikos Doukas Kamateros, and brother of Empress Euphrosyne Doukaina Kamatera, wife of Alexios III Angelos( r. 1195 – 1203).
A relative of the imperial family—his grandmother Irene Doukaina was probably a daughter of the" protostrator" Michael Doukas, brother- in- law of Alexios I Komnenos( r. 1081– 1118) —he held the high rank of" sebastos", and by 1166 held the office of" protonotarios".
By 1182 he had advanced to the post of" logothetes tou dromou", but was dismissed, blinded( apparently only in one eye), and banished to Russia when Andronikos I Komnenos( r. 1182–1185) took power.
He returned to Constantinople and was again" logothetes tou dromou" under Isaac II Angelos( r. 1185 – 1195), and remained active at court under his brother- in- law Alexios III.
After the Fourth Crusade he fled to the Empire of Nicaea, established by his nephew Theodore I Laskaris, who in 1209/ 10 sent him on an embassy to the King of Armenian Cilicia, Leo I.
Alexios III Angelos
Alexios III
Angelos  (1211) was Byzantine Emperor from March 1195 to July 17/18, 1203.
A member of the extended imperial family, Alexios came to throne after deposing, blinding, and imprisoning his younger brother Isaac II Angelos.
The most significant event of his reign was the attack of the Fourth Crusade on Constantinople in 1203, on behalf of Alexios IV Angelos.
Alexios III took over the defense of the city, which he mismanaged, then fled the city at night with one of his three daughters.
From Adrianople, and then Mosynopolis, he unsuccessfully attempted to rally his supporters, only to end up a captive of Marquis Boniface of Montferrat.
He was ransomed, sent to Asia Minor where he plotted against his son-in-law Theodore Laskaris, but was eventually arrested and spent his last days confined to the Monastery of Hyakinthos in Nicaea, where he died.
Charles Francis Norton
Charles Francis Norton( 1807 – 1835) was a 19th- century Member of Parliament for Guildford.
Norton was also a Captain of 52nd Light Infantry; son-in- law of Sir Colin Campbell; brother- in- law of writer Caroline Norton
Greg Penner
Gregory B. Penner( born December 18, 1969) is an American businessman and venture capitalist.
Penner was named the chairman of Walmart on June 5, 2015.
He is the son-in- law of S. Robson Walton and the grandson- in- law of Sam Walton, the founder of Walmart.
Anna Komnene Angelina
Anna Komnene Angelina or Comnena Angelina( c. 1176 – 1212) was an Empress of Nicaea.
She was the daughter of the Byzantine Emperor Alexios III Angelos and of Euphrosyne Doukaina Kamatera.
Euphrosyne Doukaina Kamatera
Euphrosyne Doukaina Kamaterina or better Kamatera (– 1211) was a Byzantine Empress by marriage to the Byzantine Emperor Alexios III Angelos.
Euphrosyne was the daughter of Andronikos Kamateros, a high-ranking official who held the titles of "megas droungarios" and "pansebastos" and wife, an unknown Kantakouzene.
She was related to the Emperor Constantine X and Irene Doukaina, empress of Alexios I Komnenos.
Both of her brothers had rebelled against Andronikos I Komnenos; one was imprisoned and the other was blinded.
Robert W. Levering
Robert Woodrow Levering( October 3, 1914 – August 11, 1989) was a U.S. Representative from Ohio, son-in- law of Usher L. Burdick and brother- in- law of Quentin N. Burdick.

Question: Who is Euphrosyne Doukaina Kamatera's sibling-in-law?
Answer: Isaac II Angelos