Couldn't you start a class action against one named defendant, and use the discovery process to uncover all the other unknown-at-the-time-of-filing defendants?

Couldn't you start a class action against one named defendant, and use the discovery process to uncover all the other unknown-at-the-time-of-filing defendants? I'm pretty sure that if the named defendant coughs up an NDA that prevents them from disclosing the names of their business associates to a court, the judge is not just going to say, "I'll allow it."