I don't know if there is an add-on capable of doing this or if its something default already but if not I think this should be default.
Basically, you load a save called "House". Then you load a save called "Cliffs". Lets say these saves have a lot of bricks (high brick count) and you decide to get rid of the cliffs and just keep the house, you need to clear all of the bricks and then re-load the house to get just the one save you wanted. This "feature" would keep a log of save names and bricks that belong to each save so that when you click "Clear Bricks" theres another tab or something where you can clear certain saves.
Benefits:
Main benefit is that you can have something similar to a "Lobby". Players will remain in there while other saves are being removed/added into the game. This way cyclying maps would be something very easy to do, imagine this being implemented by default (if its not already and I havent discovered this) with Greek2Me's BuildCycle Add-on (in beta or so I think).