We can save reusable modules as subassemblies in the Kerbal Space Program Vehicle Assembly Building (VAB) and the Spaceplane Hangar (SPH).
Misleading assembly list display
This is a very dangerous feature. Every subassembly is listed in the main folder, subfolders are just for display purposes to list fewer items. So DO NOT clean up subassemblies from the main folder thinking those are duplicates, as those will disappear from the subfolder too.
Setting a new root
Every subassembly can be attached by the root point. It is the first part placed in the editor during construction. If you want to attach the subassembly by another part when you use it use the re-root tool.
- Load the subassembly
- Click the Re-root tool in the upper left corner.
The toolbar disappears when you click the “New” button and loading a subassembly does not display it again. If this toolbar is not displayed, exit the building and return.
- When the prompt “Select a set of two or more parts to Re-root” and you are working on a vessel this step selects the entire craft or a portion of it. If you work with a subassembly, select the part to set as the new root.
- The new root appears on the vessel