I was on a UA ticket (Moline - ORD - EWR) flight this week scheduled for 7PM. I wanted to change my flight to an earlier departure at 4:20. When I checked in online it offered me the option to standby for the 4:20 flight but it still had me on my original 9PM flight from ORD to EWR. I knew there were earlier flights from ORD to EWR so I called United. The agent I spoke to said that there were flights at 6 and 7 from ORD to EWR but those flights are operated by CO even though they had UA flight numbers. She said I could standby for both the Moline and ORD flights but since my flights will be operated by 2 separate airlines, I would have to pay the $50 standby fee twice. Is this correct? I declined and chose to make a confirmed change for $150 instead. I have flown standby before but only for single leg flights not routes with connecting flights. Not sure how standby changes works for connecting flights. Should this have been more seamless since the flights I am talking about were operated by CO and UA?