Notwithstanding any other provision of law, except provisions of law governing the retention and storage of data, a family law court shall, upon request from the court in any county hearing a probate guardianship matter proceeding before the court pursuant to this part, provide to the court all available information the court deems necessary to make a determination regarding the best interest of a child, as described in Section 3011 of the Family Code, who is the subject of the proceeding. The information shall also be released to a guardianship investigator, as provided in subdivision (a) of Section 1513, acting within the scope of his or her duties in that proceeding. Any information released pursuant to this section that is confidential pursuant to any other provision of law shall remain confidential and may not be released, except to the extent necessary to comply with this section. No records shared pursuant to this section may be disclosed to any party in a case unless the party requests the agency or court that originates the record to release these records and the request is granted. In counties that provide confidential family law mediation, or confidential dependency mediation, those mediations are not covered by this section.