Guy, Constable of Cyprus
Guy of Poitiers- Lusignan( 1275/80- 1303) was constable of Cyprus from 1298.
He was the youngest son of Hugh III of Cyprus( 1267- 1284) and Isabella of Ibelin.
He married Eschiva of Ibelin, Lady of Beirut.
Their children were:
Hugh III of Cyprus
Hugh III of Cyprus (1235 – 24 March 1284), born Hugues de Poitiers, later Hugues de Lusignan
(he adopted his mother's surname "de Lusignan" in 1267), called the Great, was the King of Cyprus from 1267 and King of Jerusalem from 1268 (as Hugh I of Jerusalem).
He was the son of Henry of Antioch and Isabelle de Lusignan, the daughter of king Hugh I of Cyprus.
He was a grandson of Bohemund IV of Antioch and thus a descendant of Robert Guiscard.
From 1261 he served as Regent for Hugh II of Cyprus in Cyprus, as the "Haute Cour" of Cyprus considered him, as a male, a better regent than his mother Isabella.
She was, however, accepted as the Regent of Jerusalem in 1263.
She died in 1264, and Hugh became the acting regent of the Kingdom of Jerusalem as well as Cyprus.
The regency was contested by his first cousin, Hugh of Brienne, who was the son of Mary of Cyprus, the eldest daughter of Hugh I and hence the senior heir to Cyprus, and heir to Jerusalem after Hugh II.
However, the "Haute Cour of Jerusalem" declared Hugh of Antioch the next regent, as successor to Isabella in proximity of blood.
Hugh II died in 1267 without heirs.
As Hugh of Brienne did not advance his claim on the throne, Hugh of Antioch succeeded as uncontested King of Cyprus on 5 December and was crowned at Santa Sophia, in Nicosia, on 24 December.
He claimed the Kingdom of Jerusalem as well in 1267 or 1268 upon the execution of Conradin.
However, the throne of Jerusalem was also claimed by Mary of Antioch by proximity of blood to Conradin.
The "Haute Cour of Jerusalem" rejected her claim and Hugh was crowned King of Jerusalem at Tyre on 24 September 1269.
Hugh and his descendants, the Kings of Cyprus, assumed his mother's surname of Lusignan in 1267, having inherited Cyprus through that family, thus establishing the Second House of Lusignan.
Hugh disliked dealing with the various factions in the Kingdom of Jerusalem, and left for Cyprus in 1276 in disgust at their defiance of his authority.
The next year, his bailiff, Balian of Ibelin, Lord of Arsuf, was ejected by Roger of Sanseverino, the bailiff of Charles of Anjou, who had purchased the claim of Mary of Antioch.
The kingdom remained under Angevin control for the rest of Hugh's reign.
It is supposed that Thomas Aquinas' work "On Kingship" was written for Hugh III.
He was buried at Santa Sophia, in Nicosia.
Marie of Lusignan, Queen of Aragon
Marie of Lusignan (1273 – Tortosa, April 1319) was a daughter of Hugh III of Cyprus and his wife Isabella of Ibelin.
She was Queen of Aragon by her marriage and was a member of the House of Poitiers-Lusignan.
Isabella of Ibelin, Queen of Cyprus and Jerusalem
Isabella of Ibelin (1241–1324), was Queen of Cyprus and Jerusalem by marriage to Hugh III of Cyprus.
She was the daughter of Guy d'Ibelin, marshal and constable of the Kingdom of Cyprus, and of Philippa Berlais.
She married Hugh III of Cyprus (1235–1284), the King of Cyprus
(reign 1267–1284).
John of Ibelin (died after 1250)
John of Ibelin(" Jean d' Ibelin", died after 1250) was a member of the House of Ibelin and a crusader to the Kingdom of Cyprus.
He was the son of Baldwin of Ibelin, seneschal of Cyprus, and of Alice de Bethsan.
He married Isabelle du Rivet, daughter of Aimery du Rivet and Echive de Saint- Omer.
They had:
Guy of Ibelin, seneschal of Cyprus
Guy of Ibelin
( French:" Guy d' Ibelin")( before 1306 – 1350/60) was seneschal of Cyprus from 1318 and a burgher of Venice from 30 December 1334.
He was the son of Philip of Ibelin( 1253 –1318), previous seneschal of Cyprus and Jerusalem by his second wife Maria of Giblet( d. 1331).
He was evidently held in high regard by King Hugh IV of Cyprus, since he is named in a royal decree from 1329 as a magnificus vir, in charge of four newly created priesthoods in the cathedral of Nicosia.
He married Margaret of Ibelin with papal dispensation in 1319.
They had three children:
Guy of Ibelin (1286–1308)
Guy of Ibelin( 1286–1308), Lord of Nicosia, was the son of Balian of Ibelin, seneschal of the kingdom of Cyprus, and of Alice of Lampron.
In 1303, with papal dispensation, he married his cousin Isabella of Ibelin, daughter of Baldwin of Ibelin and of Marguerite de Giblet.
Their only child was Alix of Ibelin, second wife of Hugh IV of Cyprus.
Guy was buried on September 8, 1308 in the Premonstratensian Abbey of Bellapais near Kyrenia, Cyprus.
Isabella of Ibelin (died 1315)
Isabella of Ibelin( died 1315) was the daughter of Baldwin of Ibelin( d. 1313), lord of Korakou, and of Marguerite de Giblet.
Constance of Sicily, Queen of Cyprus
Constance of Sicily( 1304 /1306 – after 19 June 1344) was Queen of Cyprus and Jerusalem by marriage to Henry II of Cyprus and Queen of Armenia by marriage to Leo IV of Armenia.
Helvis of Ibelin
Helvis of Ibelin( after 1178 – before 1 June 1216) was a daughter of Balian of Ibelin and his wife, Maria Komnene, who was the dowager Queen of Jerusalem.
Helvis was a member of the House of Ibelin.
She was Lady of Sidon by her first and second marriage.

Question: Who is the father-in-law of Isabella Of Ibelin, Queen Of Cyprus And Jerusalem?