There are more tears in the reignited custody battle between Johnson’s Baby Shampoo heiress Libet Johnson and her diet guru ex-boyfriend.

Johnson, 65, has quietly filed a contested proceeding against Dr. Lionel Bissoon, 54, in Manhattan Supreme Court.

She’ll ask a judge in March to modify a co-parenting agreement she hatched with Bissoon in 2011 for their now 11-year-old son William, according to court records.

It’s a nasty turn after the former couple appeared to be getting along having settled a wrenching, six-year custody fight over the child in 2013.

Johnson adopted the boy from Cambodia when he was 6 months old.

A prior judge had allowed Johnson to be the legal adoptive mother with a nod to her fortune. “Adoption will offer such a child numerous economic benefits, including significant right of financial support from both of his parents,” Judge Kristin Booth Glen wrote.

Bissoon’s lawyer, Bonnie Rabin, said the new custody suit is “completely avoidable and unnecessary.”

A spokesman for Johnson shot back, “William’s well-being is our family’s top priority.”