If you draw additional lines between shapes in a diagram, they won't move with your shapes when you move them around the drawing area. By using actual connectors (not lines), your diagram becomes much more flexible and easy to work with. There are four different ways you can create connectors between shapes and quickly extend your diagrams in draw.io.
You can quickly swap a shape in-place in draw.io. Drag the new shape from the library on top of the old shape until you see the swap icon appear, then release. Swapping shapes in-place in draw.io
Have you tried the floorplan stencils in draw.io? You can open the library directly by using the libs parameter, https://www.draw.io/?libs=floorplan. Or, you can enable them in your library section by clicking "more shapes" (bottom right) and ticking "floorplans", then apply: The floorplan library in the more shapes dialog in draw.io Then you [...]