[1] Her brother was José Joaquín de Silva-Bazán, director of the Royal Spanish Academy (1776-1802).

Her close friend was her housekeeper, María Ana de Abad y Albret-Bearne (1759- 1801).

In 1775, she became engaged to José María Pignatelli de Aragón y Gonzaga, III Duke of Solferino, but his sudden death upset Mariana's plans.

However, on 15 January 1775, in Madrid, Mariana married his father, Joaquín Atanasio Pignatelli de Aragón y Moncayo, XVI Count of Fuentes,[1] VI Marquis of Mora and IV Marquis of Coscojuela.

He was Antonio Ponce de León, 11th Duke of Arcos,[1] XVIII Duke of Nájera, XIV Duke of Maqueda, II Duke of Baños, VIII Duke of Aveiro (in Portugal), XV Marquis of Zahara, XV Marquis of Elche, XII Marquis of Belmonte, XII Count of Bailén, XI Count of Casares, XXII Count of Treviño, XXI Count of Valencia of Don Juan and XII Lord of Villagarcía.