ggIFCConvertId
The ggIFCDiff routine can detect changes between two ifc files, and then generates a third file defining only the changes. You can then import this delta, saving on lots of time in the model.
It might be worth getting a review of the delta by the model authors.
ggIFCExtractIds
ggIFCFindId
ggIFCOptimize
ggIFCOptimizeFolder