Blake Lively‘s lawyers are asking a judge to force Justin Baldoni, Wayfarer Studios and others to hand over financial records … claiming that if they want to sue for $400 million, they have to prove they really lost that much.

The actress’s team sent a letter to the judge Friday requesting the parties involved in the lawsuit filed against her cough up the records … which they say they’ve already tried to obtain

Lively’s team claims they met with counsel for Baldoni’s side and asked for them to hand over the documents — but were told they would only be given “non-privileged documents concerning their damages” … not the docs they requested.

Remember … Justin Baldoni and Wayfarer Studios filed a $400 million lawsuit against Blake, Ryan Reynolds and the New York Times after Blake accused Justin of sexual harassment and engaging in a targeted smear campaign against her.

Lively’s side writes that — by picking $400 million in damages for allegedly hurting the reputation and livelihoods of those included in her lawsuit — Baldoni and Wayfarer are now obligated to show how they arrived at that number.

The attorneys also point out that “It Ends with Us” was a massive box office success … even though they claim the other side is now trying to point to some unspecified financial loss because of the film.

As you know, this is just the latest development in this far-ranging legal drama … which most recently saw Baldoni’s attorney serve Taylor Swift with a subpoena.

We can’t recap every development here … but, check out our timeline video touching on the key moments in this legal war.