I have a reward booking currently has all segments on UA. Now I see Air Canada has released seats on one of the segments I’m flying, and I’d prefer to fly AC since it’s a much better departure time for us, and I can check 2 bags for free (vs. on united I can only check 1 for free).

The problem is I cannot cancel— the other two segments might disappear since right now I can’t seem to find the same UA flight availability on the remaining two segments.

On the aeroplan website I can only cancel, not modify flight segments anymore.

Obviously I won’t call now. But is there any way to do this besides calling Aeroplan later this year?