My first experience with a companion certificate was pretty interesting. SC agent tried to add me to the upgrade list (after reservation was already split) and was able to manually overide the system. When I tried to see my spot on the list, it kicked me off. It was new years eve JFK-LAX and at the gate I spoke to the agent conducting boarding and since I knew all elites were already upgraded and F was half empty, I asked if he could move us both up. When we went to board he gave us new boarding passes . We ended up in coach on the return, but no complaints here.