Ok, maybe I'm not explaining the problem clearly. I'll try to make the question as simple as possible.

How do I get an object from my plan into my furniture catalogue?

'furniture' -> 'import furniture' doesn't seem to do this - it won't import an object from the plan into the furniture catalogue. Try it: first select an object in a plan and then try to import it into the furniture catalogue. If you can do it, please let me know because that is what I need to do.