Anesthesia Reporting when a Resident is Relieved by a CRNA

An anesthesiologist is in attendance from 13:00 to 16:00 with a CRNA (medical direction of only one CRNA) from 13:00 to 15:00 and the CRNA is relieved by a resident from 15:00 until the anesthesia stop time of 16:00. We would report the physician's service with the -QY modifier and the CRNA's service with the -QX modifier. If the scenario was reversed where the resident was with the attending from 13:00 until 15:00 and then was relieved by the CRNA from 15:00 until 16:00, how would we report the physician's service and how would we report the CRNA's service? Would we report a block of time for the CRNA?