How can I keep my old music on my ipod while adding new music from my new computer?

I recently bought a new computer. I have music on my icloud that switched over. However, I am from the CD generation and I have a lot of music on my old computer that is also on my ipod nano. I purchased an album on iTunes on my new computer and want to put it on my ipod. When I sync it up, it tells me I have to clear my "old library" and download my "new library". Is there a way to keep my old music on there and add my new to it?

Or a more time consuming option, is there a way to convert my CD music to the icloud? Can I, should I do that instead? Help please.