Carrie and I returned at the power plant around 10 AM Sunday. No falcons were visible. We stayed for over an hour before deciding to look elsewhere. As we were driving away at 11:30, we spotted the male perched on the same box he was seen on Saturday. We re-parked the car and unpacked the scope to get a better look at him.
About an hour later, while talking to a couple of cyclists, we noticed a 2nd falcon perched just below and to the right of the male. Going by size, it was a female, and it also had a full crop. It was facing us so we could not see her back.
Both falcons were still at that location when we left at 1:45.
The falcons were too far away to photograph with our cameras, but we are sure that one of them was Quest. Satellite data shows that she was southwest of Pickering during the morning.

The data then shows her near the power plant starting at about the same time we spotted the female.

The accuracy of the data is about 1/2 mile. The points scattered around the power plant are consistent with a transmitter located inside the plant perimeter.
Conclusion: the female is Quest.