Legal Question in Family Law in California

No. First off, property is not "gifted." "Gifted" is an adjective, not a verb. Musicians are gifted, artists are gifted, orators are gifted, brilliant children are gifted, but property is given. You were given property by your mother. With that out of the way, the reassessment form does nothing to convert a separate property gift into community property. At most it raises a question whether your mother intended it as a gift only to you, or to both of you. If your mother is still alive, she can easily put that issue to rest in a declaration or with testimony. If she has since passed away, the form of the deed conveying title to you should trump the form. The bottom line is your mother's intent controls, and the form is only one very weak piece of evidence that she might have intended to give it to both of you. If you have strong evidence of her intent only to give it to you, the form cannot change that.