San Francisco Superior Court Judge Andrew Cheng gave them time until July 29 to resolve the issues, reported Ace Showbiz.
The settlement was supposed to be reached on June 1.
However, the actor's widow, Susan Williams, and three children from the actor's previous marriage were still in disagreement about splitting some personal items.
Meredith Bushnell, attorney for Williams' children from previous marriages, said there were approximately 300 personal items, including clothing, books, bicycles, entertainment awards and some artwork, which were still in dispute after the two sides met with a mediator at a judge's suggestion.
On the other hand, the actor left most of his estate, worth around USD 100 million, to his three children, including the proceeds from the sale of a Napa County home and property.