You can move blocks from one building to another using the Transfer blocks command accessed from the Edit menu when the site contains more than 1 building. This menu option opens the Transfer blocks dialog below. Select the building containing the blocks to be copied and the building to receive the blocks and Press OK. All blocks in the source building will be moved to the destination building.
Tip: If you would like to transfer only selected blocks then you could first clone the source building, remove the blocks that are not required from the copy then transfer the remaining blocks to the destination building.
Note: You should check before starting the block transfer that none of the source blocks overlap with blocks in the destination building. Even a small overlap will cause the whole process to fail.
A Transfer block operation cannot be undone and it clears any existing undo/redo information.