On 23rd January 1512, Vlad the Younger was decapitatd by the Craiovescu family, the very people who helped him get the throne 2 years earlier. He was only 18.
Imaginary portrait of Eupraxia (drawn by me), wife of Vlad II the Dragon and possible mother of Vlad III the Impaler Consort of Wallachia (1431-1436 (?), 1436-1442,1444-1447)
An incestous niece/uncle marriage between the Balș and Racoviță families, I've found while researching the ancestors of Chris Ghika. At least 5 out of their 9 children died in childhood.
Sima Buzescu was sued thrice, twice by her cousin once removed, lady Forica (in 1608 and 1612), who sent her men to beat Sima's servants, kill her sheep and cause demage to the property and once by her niblings, Marica and Radu (II) Buzescu (in 1616). She won all three cases.