WHITE PLAINS, N.Y. >> The recent troubles of the Kennedy clan played out in two courts in New York today in cases involving sisters-in-law who were close friends.

A test of blood taken from Kerry Kennedy after a drugged-driving arrest showed traces of a sleeping drug, contradicting her own doctors’ findings. And the oldest son of Robert Kennedy Jr. and estranged wife Mary Kennedy stepped forward to take over the estate Mary Kennedy left behind when she hanged herself.

The blood test, filed in North Castle Town Court and first reported by Newsday Westchester, showed that a toxicologist detected 14 nanograms per milliliter of zolpidem, the sleep aid found in Ambien, in a sample taken the day Kerry Kennedy’s Lexus swerved across Interstate 684 and swiped a tractor-trailer.

That amount is low, typical of someone who would have just taken a pill or taken one several hours before, said Dr. Michael Thorpy, director of the sleep disorder center at Montefiore Medical Center in New York.

A urine sample was negative for alcohol, the toxicologist wrote.

Kennedy, 52, pleaded not guilty July 17 to a charge of driving while drug-impaired. She was released but was ordered to undergo evaluation by a substance abuse agency. She is due back in court Aug. 14.

Earlier today, in Surrogate’s Court in White Plains, a dispute over who would handle Mary Kennedy’s estate was settled at least temporarily when Conor Kennedy, her son with Robert F. Kennedy Jr., applied for the job.

Conor Kennedy’s lawyer, Brandon Sall, said his client turned 18 on Tuesday, qualifying him to administer the estate of Mary Kennedy, who hanged herself in May in the midst of a divorce.

A lawyer for Robert Kennedy — who would normally be the court’s first choice to handle the estate — raised no objection, and Judge Anthony Scarpino said he expects to grant Conor Kennedy’s application.