Conversation so far:
What were Giuseppe Verdi's first operas?
Oberto, Un giorno di regno, and Nabucco.
Why did Giuseppe Verdi ask for Pietro Massini's assistance?
What was oberto?
Oberto, Conte di San Bonifacio is an opera in two acts by Giuseppe Verdi to an Italian libretto by Temistocle Solera
What other operas did Giuseppe Verdi perform besides oberto
Giuseppe Verdi performed Un giorno di regno

Question: Who was she?
Self-contained rewrite: Who was Margherita Barezzi?