In 1585 Giberto died in Piacenza under mysterious circumstances and her son Girolamo was invested by Ottavio Farnese, Duke of Colorno, with the obligation to acquire the surname and the coat of arms of the House of Sanseverino, native to the Kingdom of Naples.

By speculating on hereditary quarrels, the Duke started to claim that the investiture of Colorno to the Sanvitale family had to be considered null; thus began a lawsuit based on the feudal law, in which the most notable jurists of the time were involved.

[5] However the plan went differently since one of the servants of Gianfrancesco, imprisoned and tortured for some reasons not related to the conspiracy, exposed several names and statements which alerted the justice.

The Duke of Mantua threatened to take up arms against the Farnese, but first Pope Paul V and then the Kings of France and Spain and Charles Emmanuel of Savoy mediated and a compromise was found.

[6] The case of Barbara Sanseverino and the conspiracy was recounted by Alfredo Zerbini in the historical poem, written in Parmigiano dialect, La congiura di Feudatäri, published in 1947.