Thank you Ma'am
California law does include "grandparents rights"
The California Family Code 3103-3104 permits grandparents to litigate visitation
rights if a child’s parents are not married, even on the objections of both parents.
The court must find that there is a preexisting relationship between the grandparents and the grandchild such that visitation is in the child's best interest, AND the court must balance the interest of the child in having visitation with the parents' right to exercise their parental authority. (See Family Code, Section 3100 et seq.)
Factors considered by the court are: (1) child's preference (if child is old enough); (2) desire and ability of each parent to allow relationship with other parent, and (3) child's health, safety and welfare. (see Family Code § 3020-3424.)
Thus, as a grandparent, especially in the situation you describe, you can file a petition for custody/visitation and it would likely be granted by the courts...but understand that to start this process you would need to have a local attorney prepare and present the case to the court.
Bottom line: California has grandparents rights...and based on what you describe, it sounds like you can enforce them in your case.