Might be just me, but I don't really care who the ramp thinks is the Capt.

Try to operate my Flights as a crew-if the FO wants to add a reasonable amount of gas-then we add the fuel.

If the FO is talking to the ramp, he is doing so because I have delegated my authority for him\her to do so. I retain the responsibility, but I am not so insecure as to reject an idea simply because it comes from my FO.

Again, might be just me, but absolutely every single one of my FOs has been a Capt-Somewhere