Ferdinand I of Bulgaria
Ferdinand I (26 February 1861 – 10 September 1948), born Ferdinand Maximilian Karl Leopold Maria of Saxe-Coburg and Gotha, was the second monarch of the Third Bulgarian State, firstly as ruling prince ("knyaz") from 1887 to 1908, and later as king ("tsar") from 1908 until his abdication in 1918.
He was also an author, botanist, entomologist and philatelist.
Elena-Evgenia, wife of Ivan Asen I
Elena was the second wife of tsar Ivan Asen I of Bulgaria.
She was the mother of tsar Ivan Asen II of Bulgaria.
Ana-Neda
Ana- Neda( Bulgarian and; fl. 1323- 1324) was the Empress consort of Bulgaria briefly in 1323- 1324 as the spouse of" Despot of Vidin" Michael Shishman who was elected as Emperor of Bulgaria in 1323.
She was the daughter of Serbian King Stefan Uroš II Milutin and Princess Ana Terter, daughter of George I of Bulgaria.
From the marriage with Michael, they had three sons, one of whom was Ivan Stephen of Bulgaria, later briefly the Emperor of Bulgaria( 1330 – 1331).
Agatha (wife of Samuel of Bulgaria)
Agatha was the wife of Emperor Samuel of Bulgaria.
Simeon Saxe-Coburg-Gotha
Simeon Saxe- Coburg- Gotha( born 16 June 1937) or Simeon Borisov Sakskoburggotski, known formerly or by courtesy as Tsar Simeon II, was the last reigning Tsar of Bulgaria from 1943 to 1946, before later serving as Prime Minister of Bulgaria from 2001 to 2005.
During his reign as Simeon II, Tsar of Bulgaria, he was a minor, with royal authority being exercised over the tsardom on his behalf by a regency led by Simeon's uncle Prince Kiril, General Nikola Mihov and the prime minister, Bogdan Filov.
In 1946 the monarchy was abolished as a consequence of a referendum, and Simeon was forced into exile in Spain.
He returned to his home country in 1996, formed the political party National Movement for Stability and Progress( NMSP) and was elected Prime Minister of the Republic of Bulgaria from July 2001 until August 2005.
In the next elections, as a leader of NMSP, he took part in a coalition government with the ex-communist party BSP.
In 2009, after NMSP failed to win any seats in Parliament, he left politics.
Simeon is one of the two remaining living heads of state from the time of World War II( the other is Tenzin Gyatso, 14th Dalai Lama of Tibet), the only living person who has borne the title" Tsar", and one of only two former monarchs in history to have become head of government through democratic elections( the other is the now- deceased Norodom Sihanouk of Cambodia).
Kiril, Prince of Preslav
Prince Kyril of Bulgaria, Prince of Preslav (Kyril Heinrich Franz Ludwig Anton Karl Philipp; 17 November 1895 – 1 February 1945) was the second son of Ferdinand I of Bulgaria and his first wife Marie Louise of Bourbon-Parma.
He was a younger brother of Boris III of Bulgaria and a prince regent of the Kingdom of Bulgaria from 1943 to 1944.
Keratsa of Bulgaria
Keratsa-Maria of Bulgaria( 1348–1390) was Princess of Bulgaria during the Second Bulgarian Empire and Empress of Byzantine Empire.
She was the daughter of Tsar Ivan Alexander of Bulgaria and his second wife, a converted Jew, Theodora.
Minamoto no Chikako
She was the mother of Prince Morinaga.
Desislava of Bulgaria
Desislava of Bulgaria was daughter of Tsar Ivan Alexander of Bulgaria and his second wife Theodora, a converted Jewish woman.
Irene Komnene Doukaina
Irene Komnene Doukaina or Eirene Komnene Doukaina was an Empress of Bulgaria during the Second Bulgarian Empire and Byzantine princess.
She was the third wife of tsar Ivan Asen II of Bulgaria.
She was the mother of tsar Michael Asen I of Bulgaria.

Question: Where did Kiril, Prince Of Preslav's father die?