A former publicist for the actor and director Justin Baldoni filed a lawsuit on Tuesday that adds a new dimension to an alleged campaign to undermine the actress Blake Lively. The publicist, Stephanie Jones, said she was forced out of representing Mr. Baldoni and his film studio amid concerns that Ms. Lively would go public with accusations of misconduct against him.

Ms. Jones’s lawsuit, filed in New York and alleging breach of contract, follows a separate legal complaint in California on Saturday by Ms. Lively. The actress asserted that Mr. Baldoni; his film studio, Wayfarer; and their public relations representatives retaliated against her after she raised her misconduct allegations during the filming of “It Ends With Us.”

Ms. Lively’s legal complaint included excerpts from thousands of pages of text messages and emails that she had obtained through a subpoena. Ms. Jones’s lawsuit reveals that those messages came from a company phone used by one of her former employees, Jennifer Abel, who was among those Ms. Lively accused of helping to orchestrate a smear campaign against her.

Ms. Jones said she fired Ms. Abel last summer after discovering that Ms. Abel had been stealing documents from her firm as she prepared to start her own business. According to the lawsuit, the phone was voluntarily returned to Ms. Jones’s company, Jonesworks, “in the presence of an employment lawyer,” and the messages and emails “were forensically extracted directly from that company phone” and “have been preserved in their original state.”

Ms. Abel had been the Jonesworks point person for Mr. Baldoni and Wayfarer, and the messages show that she worked closely with Melissa Nathan, a crisis communications manager, as soon as Wayfarer and Mr. Baldoni hired her. The lawsuit says that Ms. Jones saw the messages from the phone after she fired Ms. Abel and Wayfarer stopped working with Jonesworks.