In the fuel planner of the Airbus I lower the planned fuel quantity. For example when the planner wants to load 6845 kg of fuel, I change the 6 into a 1. Then I let the Airbus read the data from the load planner and do a instant load. Now 1845 kg of fuel is on board.
Next I let do the fuel planner the calculation again and let the Airbus read the data from the fuel planner again.
After that I call the fuel truck. When the fuel truck arrives it will tell you to start loading fuel in the airbus MCDU. Now the fuel truck will start to load 6845 - 1845 kg of fuel.
When the quantity of fuel is equal to the planned fuel in the fuel planner the fuel truck will not do anything.
Best regards,
Snoopy_belgium