Britney Spears could be headed for more legal drama — but this time it will involve her sister.

Jamie Lynn Spears just released a new memoir titled, “Things I Should Have Said.” The book tells stories about issues that came with growing up in the Spears family.

Britney’s lawyer has sent a cease-and-desist letter that threatens legal action if Jamie Lynn continues to make any derogatory references about Britney while promoting her new book.

Britney has taken to Instagram to call out Jamie Lynn and question claims made in her book.

One post, in part, reads: “…and I’m sorry Jamie Lynn, I wasn’t strong enough to do what should have been done…slapped you and Mamma right across your *expletive” faces!!!!”

Jamie Lynn’s book was released January 18.