Is there something particularly far fetched about in orbit refueling? In-orbit docking and pressure equalization is a long solved problem. Is there something I don't know about?
For any liquid in microgravity the name of the game is ullage. Gasses will self-equalise, but liquids clump together and stubbornly refuse to move the way you want them to.
The typical solution, which is in the context of relighting a liquid fueled rocket that is coasting in microgravity, is to use some other engine to push the fuel in one direction, providing enough initial ullage to light the main engine after which the thrust from the main engine provides the rest.
For refueling it is normally assumed that the target and resupplier are stationary when docked, or at least not accelerating to their next set of orbital parameters; they are station-keeping. The typical solution doesn't work there, so there is research to be done on just how the refueling will work in practice.
