Legal Question in Real Estate Law in California

First of all, it sounds as though the law of the Philippines, rather than California law, is going to apply here. You don't give enough information for me to be sure, but I think you'll need to consult with an attorney who is familiar with, or licensed in, the Philippines.

In California, cases like this that go to court are usually decided based on the judge's opinion as to whether the omission of an heir (or potential heir) was accidental or intentional. For that reason, lawyers are taught to draft wills so that it is very clear that someone's omission from the will was intended ....... i.e., by leaving Joe with $1 instead of omitting all mention of Joe from the will.

Although I can't guess how a Philippines court would rule, in California it's possible that a "will contest" in court would result in a judge determining that your omission was an accidental oversight. If it were found to be intentional, or even if there were uncertainty as to the testator's intention, you'd lose, and the will would be enforced as written.

I'm sorry; in my previous answer I referred to a "will" rather than a "deed of donation" as the questioned instrument. That was my mistake...... ...however, I think (at least, in California) that the same rules regarding mistake on the part of the person executing the instrument would apply, and the result would be the same.