A lawsuit involving the three surviving children of Martin Luther King Jr. and Coretta Scott King is threatening to derail a $1.4 million deal for a book on their mother.

The New York-based Penguin Group agreed to pay $1.2 million plus royalties to King Inc., which controls the civil rights icon's intellectual property. The publisher would pay another $200,000 to the Rev. Barbara Reynolds, who taped conversations with Mrs. King before she died in January 2006.

This week, Penguin said it would terminate the contract and demand the return of a $300,000 advance if the publisher does not receive photos, personal writing and letters within seven business days.

A message was left Friday with Penguin general counsel Karen Mayer.

The lawsuit — the third among the three siblings in as many months — was filed Sept. 24 in Fulton County probate court. Bernice King is listed as plaintiff and administrator of her mother's estate, and the estate of Martin Luther King Jr., which Dexter King controls, is listed as the defendant.

The siblings are feuding over whether the documents should be turned over. Bernice King and Martin Luther King III maintain that their mother no longer wanted to work with Reynolds on the book. They are asking that the documents be distributed among Coretta Scott King's heirs and not given to the publisher.

Dexter King, president and chief executive officer of King Inc., signed the book contract.

Craig Frankel, Dexter King's personal attorney, said his client was within his rights to sign the contract and had discussed the deal with his siblings.

"He signed the contract, but that's his job," Frankel said. "No one questioned when they got their share of the sale from the King papers whether Dexter had the authority to sign a contract. Nobody complained when they got their millions."

Also at issue is whether Coretta Scott King's biography is part of King Inc., since it was not part of the 10,000-document collection auctioned by Sotheby's in 2006 in a $32 million, eleventh-hour deal brokered by the city of Atlanta. The siblings have received equal shares of the money.

Coretta Scott King died in January 2006.

Jock Smith, an attorney for Bernice and Martin Luther King III, said his clients had no knowledge of the book deal until they were asked to turn over the documents a few weeks ago.

"This basically comes down to a situation where Dexter has done things on his own," Smith said.

Smith added that such actions were the basis for a separate lawsuit filed in July by Bernice and Martin Luther King III attempting to force their brother to open the books of their father's estate. In August, Dexter King sued them, alleging that they each established foundations that compete with The King Center.

All the cases could be resolved before they make it to a courtroom, though prospects for a meeting between the estranged siblings were unclear.

"Ideally, I don't think anybody is opposed to discussion, but that has to start with a board meeting to rectify the wrongs that have occurred here," Smith said. "I'll tell you this: There has been no meeting called since the death of Coretta Scott King."