Update:

A number of concierges in YYZ, YOW, YUL have been very helpful in providing numbers and/or checking offices for me. A couple including Grace in YYZ have been nice enough to walk to custom and check on this for me.

I have been following up myself with calls to different custom and airport lost and found. I also contacted lost passport hot line and got a call back from the duty officier who told that I might be able to get emergency replacement Monday during the day for the express fee. I was almost resigned to going through the lost passport and emergency replacment process tomorrow and was making one more call before heading out to get my photo taken for the replacement passport process tomorrow.

That call to YUL yielded another number in YUL and someone in YUL had found my passport !!!! I guess I left it on the plane and YOW and YYZ did not locate it and YUL found it and turned it in at YUL before an AC Concierge caught up with the plane in YHZ.

I have to wait till tomorrow morning since the office where it had been turned into is not open over the weekend. Not sure if someone else can pick it up for me or if I have to route myself via YUL to pick it up. I have already paid a change fee to change my ticket from Sunday 3pm to Monday 5pm YOW-YYZ-ATL so may have to pay another fee to route via YUL to pick it up if I can...

Thanks to all for the help, advice and support...
Mary