(a) An individual entitled to notice under §§ 16-4501 through 16-4524 (the Uniform Child Custody Jurisdiction Act) [repealed] may challenge a standby guardianship designation order by initiating a child custody proceeding in the Superior Court of the District of Columbia or in any court that could exercise jurisdiction in accordance with §§ 16-4501 through 16-4524. (b) An order of custody issued by a court of competent jurisdiction supersedes any designation of standby guardianship.