Sometimes you did work to design a car, and you just did hardly a wheel. What can you do? You will copy/paste it and you will be ready to go. What if someone else did a car frame, you did the engine, and you want to combine your work?
NaroCAD had previously no way to do it. Right now two tools are ready to help you: Import from NaroXml which basically will do rebuild the shapes with re-based indices, and an export tool, which will save just the selected shapes.
Probably this will make easier sharing and will improve the way you design shapes by splitting your design in parts.