Since Britney Spears’ conservatorship was terminated in November, Spears has been speaking out against various members of her family. Now, as the BBC reports, Spears’ lawyer Matthew Rosengart has issued a cease-and-desist letter to her sister Jamie Lynn Spears to warn her against saying any further “derogatory” statements about Britney while promoting her new memoir Things I Should Have Said.

Last week, Jamie Lynn Spears gave an interview to Good Morning America to promote her memoir, in which she characterizes Britney’s behavior before the conservatorship as “erratic,” “paranoid,” and “spiraling.” Britney responded to the interview in an Instagram post, saying that Jamie Lynn “never had to work for anything” and that she was barely around during the time in question. Britney also denied a section of Jamie Lynn’s memoir where she accuses the pop star of locking herself and Jamie Lynn in a room while “grabbing a knife.”

The cease-and-desist letter says that Jamie Lynn’s memoir contains “misleading or outrageous claims,” and says that Britney believed Jamie Lynn has “exploited her for monetary gain.”

“Publicly airing false or fantastical grievances is wrong, especially when designed to sell books. It is also potentially unlawful and defamatory,” the letter reads. “You recently reportedly stated that the book was ‘not about her.’ She takes you at your word and we, therefore, demand that you cease and desist from referencing Britney derogatorily during your promotional campaign. If you fail to do so or defame her, Britney will be forced to consider and take all appropriate legal action.”

In other Spears’ legal news, her lawyer is also fighting back against her father’s demand that she pay his legal fees. As The New York Times reports, newly-filed court papers accuse Jamie P. Spears and others associated with the conservatorship of financial impropriety. Jamie P. Spears’ lawyers had previously said that Britney Spears’ estate should pay for legal expenses to properly close out the conservatorship.