That is an interesting one for sure. Wanting to have an existing model that is raised up and that it is still existing?
I model renovations mostly probably, I don't think a proposition like that would ever come to fruition here in Finland 😁 (Love to see Australians hauling whole buildings with a truck to some other place and use it. Only timber frames moved here 😁)
But if you insist on it being a existing structure I would either (depending on the actual plan on how to do it):
I would think how the actual process would be done and model in phases accordingly. So if the existing building would be crained to the side, then the new part would be built and then crane it back; then model it like that.
OR model the existing lifted part as a link and work it through there?
Filters most likely will have to be used in views if you want to make it look sharp.
PICNIC: Problem In Chair Not In Computer.
Around 90% of issues can be explained by human error instead of an actual error.