...
BLPU Extent Manager is a batch tool to quickly capturing Provenances (BLPU Extents).
...
b) Hold SHIFT button and drag the mouse to confirm multiple Land Registry polygons to multiple BLPUs in one move (handy for rows of terraced houses),
c) Hold CTRL button and drag the mouse to capture a single BLPU extent made of TopoArea polygons – polygons will be automatically merged (note that you should not use this method for capturing multiple BLPUs at once).
Please note that in In this example, captured polygon is assigned to all four BLPUs.
...