CA Prob Code Section 3110

(a)

A proceeding under this chapter shall be brought by a petition filed in the superior court.

(b)

The proper county for commencement of the proceeding is the county in which a conservatorship proceeding of one of the spouses is pending. If a conservatorship proceeding is not pending, then in either of the following:

(1)

The county in which one or both of the spouses resides.

(2)

Any other county as may be in the best interests of the spouses.