Maybe we have different views on it, but if in FMC I have set the display of fuel in KGS and after calling a tanker, the table in LBS units is loaded, I don't know, but without another choice of setting it just seems strange to me. But what can be done, you are the creators of this project and as you decide, so it will be. The only option left for me is to refuel from the rest of the fuel by changing the numbers in TOTAL KGS. What can be done, since I won't be using the truck to fill up the fuel. It is sad.
In other aircraft such as Asobo A320, Fenix A320 or LVFR 319&321, I also do not use the method of calling a refueling truck, because I did not find the possibility of refueling in some types, because some possibilities simply do not work, the aircraft has limited possibilities, especially the incomplete Asobo A320.