In case of a homestead, if either spouse or either domestic partner shall be or become incompetent or disabled to such a degree that he or she is unable to assist in the management of his or her interest in the property of the marriage or domestic partnership and no guardian has been appointed, upon application of the other spouse or other domestic partner to the superior court of the county in which the homestead is situated, and upon due proof of such incompetency or disability in the severity required above, the court may make an order permitting the spouse or the domestic partner applying to the court to sell and convey or mortgage such homestead.