Can third-party models(SketchUp) be added to ongoing projects?
From Warehouse I downloaded a home (new+modern+house).skp
and a few other furniture models and accessories.
How do I snap any of these to ‘new+modern+house.skp’ model?
You can do it a couple of ways. With both the old and new SKP files open, you can use Edit>Copy in the old file and Edit>Paste into the new. Of course you can use the appropriate keyboard shortcuts or toolbar buttons, too.
Another way would be to save the individual furniture and accessory components to a folder on your computer and use File>Import to import them to the new house or you could open the folder as a local component collection in the Components window. Then drag the components into the new file.