Found the following article online, use it to answer the question: What were the firsts names the original preliminary ensemble?

At the court in Ferrara, a collection of ladies skilled in music inspired the composer Luzzasco Luzzaschi and caught the Duke's interest. This group, which led to the formation of the concerto delle donne, performed within the context of the Duke's musica secreta, a regular series of chamber music concerts performed for an exclusive audience. This preliminary group was originally made up of talented but amateur members of the court: the sisters Lucrezia and Isabella Bendidio, Leonora Sanvitale, and Vittoria Bentivoglio. They were joined by bass Giulio Cesare Brancaccio, who was specifically brought to the court in 1577 for his singing ability. The preliminary ensemble was active throughout the 1570s, and its membership solidified in 1577. Only later did professionals replace these original singers.
The Duke did not announce the creation of a professional, all-female ensemble; instead, the group infiltrated and gradually dominated the musica secreta, so that after the dismissal of Brancaccio for insubordination in 1583, no more male members of the musica secreta were hired. Even when Brancaccio was performing with the consort it was referred to as a ladies' ensemble, because women singing together was the most exciting aspect of the group. This new ensemble, the concerto delle donne, was created by Alfonso in part to amuse his young new wife, Margherita Gonzaga d'Este (she was only fourteen when they wed in 1579), and in part to help the Duke achieve his artistic goals for the court. According to Grana, a contemporary correspondent, "Signora Machiavella [Lucrezia], Signora Isabella, and Signora Vittoria have abandoned the field, having lost the backing of Luzzaschi". The first recorded performance by the professional ladies was on November 20, 1580; by carnival season in 1581, they were performing together regularly.This new "consort of ladies" was viewed as an extraordinary and novel phenomenon; most witnesses did not connect the second period of the concerto delle donne with the group of ladies who sang in...

Isabella