California Code, Probate Code - PROB § 3073

(a) The joinder or consent under Section 3071 of a spouse having legal capacity shall be in a manner that complies with Section 1100 or 1102 of the Family Code or other statute that applies to the transaction.

(b) The joinder or consent under Section 3071 of a conservator shall be in the same manner as a spouse would join in or consent to the transaction under the statute that applies to the transaction except that the joinder or consent shall be executed by the conservator and shall refer to the court order, if one is required, authorizing the conservator to join in or consent to the transaction.