She has asked the court to exclude the contents of the San Francisco Bay Area home she shared with Williams from the items the actor said the children should have.
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Williams' children, Zachary, Zelda and Cody, said in response that Susan Williams is "adding insult to a terrible injury" by trying to change the trust agreement and rob them of the late actor's belongings, including jewelry and memorabilia.
Susan Williams' attorney said she was only seeking guidance from the court about the meaning of certain terms in the trust.
Robin Williams died at his home in Tiburon, north of San Francisco, in August. The coroner ruled his death a suicide that resulted from asphyxia caused by hanging.
The actor's wife has said he struggled with depression, anxiety and a recent diagnosis of Parkinson's disease.
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Williams' trust granted his children his memorabilia and awards in the entertainment industry among other particular personal items, according to court documents.
Susan Williams says that because he wanted her to continue to live at the Tiburon home, it makes sense that he intended for his children only to have the specific personal items kept at another home he owned in Napa.
The two sides also disagree over items put in storage, watches Williams owned and his memorabilia.