Not sure what the question is but in BA we receive a Provisional Loadsheet which is signed and a copy left with the dispatcher. We work out our perfomance figures on that with an added safety margin.
During taxi out we receive an ACARS loadsheet. It is states either COMPLIANCE WITH ISSUE X or CHANGES FROM ISSUE X.
Compliance is when the final numbers are within given tolerances and we depart using the previously prepared figures. If changes then we have to recalculate. In practice changes rarely occur.
System works extremely well and 99.9% of us are happy to use it.