Advancements of Inheritances in CA Will

There is a Will that is currently intestate in California. Part of the Will indicates that a family member was to receive a total of 50% of the estate, which included the sharing of a co-owned stock that co-owned by that member and the member who has passed away. The member now claims that there is "no such stock" and is attempting to receive the 50% share...plus the stocks that we believe was already transferred to the member. I know that the purchase and selling of stocks is traceable and reported to the IRS and other places. We do believe that the stock was transferred to the individual ahead of testate as the death was pending. How does CA account for "advancement of gifts" in a Will? I've read that most states will take into account that the gifts named in the Will given prior to the death is considered an advancement...and in this case, the amount of the shares is to be deducted from the percentage of the estate. Is there a statue that recognizes this? Is there a CA law?