Archbishop Anthony Apuron of Agana was relieved of all pastoral responsibilities in June, after several young men came forward to say that the archbishop had molested them.
The archbishop has denied the charges. He remains officially the Archbishop of Agana, although his authority is suspended while the charges against him are investigated.
Archbishop Savio Hon Tai Fai, who was appointed in June as temporary caretaker of the Guam archdiocese, revealed in September that he is asking the Holy See to remove Archbishop Apuron permanently from his post and name a successor.
As coadjutor, Bishop Byrnes will be in line to become the Archbishop of Agana when Archbishop Apuron resigns or is removed by Pope Francis.
He was named as coadjutor “with special faculties,” suggesting that he could take over the day-to-day administration of the Guam archdiocese immediately.