Thanks, and you're right about IST-DAR. I wasn't clear. If I use the Aeroplan site and try YYZ-DAR, I don't see the TK non-stop options. I do see them come up if I try IST-DAR instead. So I guess I should break the legs down like that, and when the time comes, if all the pieces align, I call Aeroplan and spoon feed the segments?
I appreciate the UA, connect-thru-US, and ET suggestions. I'll add those to the toolbox.