Due to the Braganza curse casted by a lunatic monk against king D.João IV, all the Braganza kings from D. Afonso VI till D.Pedro IV were unintended heirs.

D.João IV (d. 1656)---heir firstborn D.Teodósio (1634-1653)---succeeded by 3rd son D.Afonso VI, deposed by 4th son D.Pedro II.

D.Pedro II (1648-1706)---heiress Infanta D.Isabel Luisa Josefa, Princess of Brazil (1669-90), stepped back from August to September 1688 for her half brother Infante D.João, regained the title of PoB and the Crown-Princess style from Sept. 1688 until October 1689

D.João V (1689-1750) --- D.Pedro Pr. of Brazil (October 1712/October 1714)--- followed by King D.José I (June 1714-1777)

Since the curse only affected male primogeniture, D.José's first born, the future D.Maria I could succeed peacefully.

Bur her firstborn fell victim of the curse.
D.José Prince of Brazil (1761-88) left his place to his younger brother D.João VI.

D.João VI's firstborn, Prince D.Francisco António, died in infancy in 1801.
When the king died in 1826 , the throne should have passed to his 2nd son D.Pedro, Emperor of Brazil, who renounce his rights in favour of his elder daughter D.Maria da Glória who should have married her uncle D.Miguel.

But D.Miguel proclaimed himself King instead.

After the civil war, the throne was established in the Bragança-Saxe-Coburg line and the curse seemed to have vanished.

D.Pedro V, the firstborn, succeeded his mother, and, having died childless, was succeeded by his next brother D.Luis, himself succeeded by his eldest son D. Carlos.

Until the curse stroke again with the regicide of the king and the crown-prince.

In Brazil the curse remained as D.Pedro II (1825-91) was the 3rd son of D.Pedro I , after D.Miguel (b. a d. 1820) and D. João Carlos (1821-22)