Things are getting lost in translation between what the agent told you and/or how you interpreted it/are reporting it here
Originally Posted by
frappant
Again, the UA agent told me he couldn't put me on the SFO-YVR flight on UA until AC released the record to them.
...
1K agent thinks he "held" that flight for me, even if he couldn't put it into the record, under the same confirmation number.
If space is "held" on a flight for you, you have a confirmed reservation for that flight and it will get treated like any other confirmed flight in the reservation in terms of canceling the itinerary and no shows. Period. Whether your ticket allows you to utilize that confirmed space is a different story, and is the issue here. If you checked in with Air Canada that locks those coupons as ticketed. Once a coupon is put in checked in status, it indicates to the validating carrier that the operating carrier intends to redeem that coupon against the ticket value, so no one can exchange that coupon for a different set of flights unless the checked in status is removed by the operating carrier.
I've made multiple posts about this before, so I'm not going to into all the details, but this resolves around the difference between a reservation and a ticket. Both are required to fly, but are distinct components of a travel itinerary.
Originally Posted by
frappant
Someone on the AC board said AC and UA have different systems which limit what either side can do to these records. Have no idea about that.
Yes they have different systems. It has no impacts on the limitations on what either side can do since both systems have to comply with IATA ticketing standards.