If looking at the schematics, you need the crossfeed open if you want both centertank pumps to participate in the transfer...
If the crossfeed is closed only the R CTR tank pump will pump fuel back to the fueling panel. If crossfeed is open both pump will pump fuel to the fueling panel. If you leave the crossfeed closed you might as well leave the L CTR tank pump off.
Now for another consideration. Are you allowed to trasfer fuel with passengers on board or boarding? Technically you are fueling tank 1 and 2, just from another source than usual
