omitted beneficiary and decedent's intent

[jumper]

Long story short. A great aunt leaves items as "specific gifts" to her grand-nieces and nephews. The aunt included all nieces and nephews, by name, in the will. However, one grand-niece was not born at the time the will was created (2005). Could it be argued that the intent of the aunt was to leave something to all her grand-nieces and nephews, which would allow the omitted niece to receive an equivalent share of the specific gift? Is there a legal precedent for this or is it entirely at the discretion of the executor?

Will is in California and has a "no contest clause". Also has an "omissions intentional" clause.

Thanks much....