I have a $400 bump certificate on US that I want to use. The route I want to fly (RDU-YYZ) has very high fares for US. I'd like to try to find a UA flight that is codeshared with US. I know UA codeshares with AC on a lot of YYZ flights, but that doesn't help me.

Any advice on how to find the UA routes that are codeshared with US?