The will was signed Aug. 1, 2000, Strom Thurmond Jr., Brown's probate attorney in Aiken, S.C., told The Augusta Chronicle.
Brown, who died last month in Atlanta at age 73, married Hynie in December 2001. James Brown Jr. had been born six months earlier, on June 11.
The exclusion has added to a dispute about the soul singer's legacy.
Brown's attorneys contend that Hynie is not Brown's widow because she was still married to another man when they said their vows. They have said Hynie later annulled her previous marriage, but she and Brown never remarried.
Hynie says she was legally married to Brown.
The will calls for Brown's personal effects to be divided equally among the singer's six adult children.
North Augusta, S.C., lawyer James Huff said that if a will specifically names some children but excludes others, the excluded children have no claim to the parent's assets, regardless of when they were born.
Huff represented Brown when he sought to annul his marriage to Hynie in 2004, a petition the singer later dismissed.
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