Need help understanding Codeshare & no upgrades
 

I had our corporate travel agent book the following:
CLE-LAX (on CO)
LAX-LIH (United)
LIH-SFO (United)
SFO-CLE (CO)

I was able to use miles (and a copay) to upgrade the United portions- However, when I went to Continental the agent first said that it was united paper and they needed United to let them access the ticket. i waited on hold and when she came back she said that "codeshare flights are not eligible for upgrade on Continental". I can't believe that CO cannot upgrade using a copay and miles a segment on their plane.. Any insight would be really appreciated..

Thanks

CO can upgrade any flight on their metal regardless of the code it was sold under but you'd have to pay CO miles/certs for the CO segments and UA miles/certs for the UA segments. You cannot get the CO segments upgraded using the same miles/certs for both right now.