I booked flights for may family once in Y since I had small children. When we checked in, United had op-upgraded me to C and left the rest of the family(3) in Y. I asked them to move me back during check-in, but was told that I would have to check with the gate. At the gate they (DUS) were clearly upset at my request and promised they we would be able to visit a few times during the flight. I put my wife in C for political reasons, but the FA were adament that we stay in our seperate cabins.