Place buildings anywhere, on top of existing things, and the game will handle it
Use the new Replace tool in the "Architect/Structure" menu to replace any building's materials. Or place a building with new stuff over an old building. New stuff is even applied to blueprints and frames.
Because Replace Stuff doesn't break down the existing building, this means:
Upgrading walls doesn't break the room, and keeps freezers indoors and cold.
Replacing workbenches keeps the bill list.
Replacing beds preserves their owner.
Probably more useful things I haven't thought of.
Upgrading buildings means you can build the new building over the old version, and it will keep the old one in place until the construction is done, and the new one should keep settings.
The list of Buildings that can be upgraded:
This type of replacement does destroy/create the thing, so certain internal data structures are re-built, but things like temperature of rooms are retained. The upgrade process has to be defined for each type, so the list is just what I thought to do.
Things that remember settings when auto-rebuilt:
Work Table - bills
Cooler/Heater - Temperature settings
Hydroponics/pots - Plant Selection
Storage buildings - storage filter settings
Again, the settings saving process has to be defined for each type, so the list is just what I thought to do.