An ugly incest scandal has come back to haunt legendary comic Tommy Smothers — and this time it could threaten to sink his marriage.

The guitar-strumming half of the Smothers Brothers comedy team made a $300,000 out-of-court settlement with his stepdaughters over a sexual molestation lawsuit in 1998, and thought his nightmare was over.

But Alana Monson DeLima, now 33, and Murlyne ‘Mimi’ Wilcock, 36 — the stepdaughters who accused him of fondling them when they were 4 and 6 years old — never received their money through the law firm that negotiated their settlement.

And now Tommy, 67, is being called back to court to testify in a case against the law firm.

“Tommy paid the settlement money — $50,000 of his own money and $250,000 from his insurance company — to his stepdaughters, and thought the awful ordeal was over and done with,” an insider declared.

“But that just isn’t the case. His name’s going to be dragged through the mud once again.”

The law firm that was handling the case for the two women, Blum & Roseman, went bankrupt, and the money disappeared.

Blum & Roseman is being brought to court by the State of California for absconding with the funds of a number of their clients, including Alana and Mimi.

“Tommy is being subpoenaed to testify in court on July 6,” said the insider. “The emotional toll this is taking on his current marriage could be devastating. He wants people to remember him for the warm comedy and music he’s made, not for those horrible sexual allegations.”

Tommy has repeatedly denied any wrongdoing with his stepchildren. And in 1998, he told The ENQUIRER exclusively: “These charges are false!”

Ultimately, he settled the case with Alana and Mimi — stepdaughters from his brief marriage to Rochelle Robley in 1974 — to avoid a lengthy and costly trial.

But now the stress of the new case is deeply affecting Marcy, his wife of 14 years.

“The sexual molestation lawsuit took a lot out of her and she’s tired of it always lurking around,” the insider disclosed.

“She hates what Tommy’s stepdaughters have done to her family. She told a friend, ‘After five years of this I can’t take any more.’ ” — TIM PLANT