If the petitioner has not mailed, as provided in this Article, a copy of the petition for letters of administration to any person, whether or not named in the petition, who is entitled to administer or to nominate a person to administer equally with or in preference to the petitioner, the person entitled to administer or nominate within 3 months after the issuance of the letters may file a petition for issuance of letters to him or to his nominee. The person entitled to preference must give 10 days notice of the hearing on his petition to the person to whom letters were issued. Upon the hearing the court may revoke the letters previously issued and issue new letters.
755 ILCS 5/9-7