Cal. Prob. Code § 9801
If property of the estate consists of an undivided interest in real or personal property, or any other interest therein less than the entire ownership, upon a showing that it would be to the advantage of the estate to borrow money to improve, use, operate, or preserve the property jointly with the owners of the other interests therein, or to pay, reduce, extend, or renew a security interest, lien, mortgage, or deed of trust already existing on all of the property, the personal representative, after authorization by order of the court obtained under this chapter, may join with the owners of the other interests in borrowing money and the execution of a joint and several note and such security interest, lien, mortgage, or deed of trust as may be required to secure the payment of the note. The note may be for such sum as is required for the purpose.
Ca. Prob. Code § 9801