Mono/Kilo
Unusable, trapped or ballast fuel will always be included in the gauges, as far as I know. Please remember that unusable fuel is a non standard situation, fuelgauges do not take that into account.
However it will not be on the flightplan as fuel, but as ballast, or other kind of nonrevenue load. Same goes for loadsheet.
For NG drivers: Did it require any change for allowing the use of all fuel in the centertank, or was it just certification issues?
FS