Syncing old songs to new devices?

(I am lost when it comes to this type of stuff) 😟 I have a 2nd generation, 8GB ipod touch. I haven't used it in a few years due to the fact of getting an ipad and Mac computer. I was wondering how I can transfer the old songs on my ipod to my new devices? When I try to sync my ipod to my computer it says that my ipod is synced with another itunes library and that my ipod can only be synced with one itunes library at a time. I can either erase and sync (it replaces the contents of my ipod with the contents of the new library) or i can transfer purchases (it copies itunes store purchases that my computer it authorized to play from the library on my ipod). I don't want to lose my old songs, and would like them on my ipad and Mac. Is it possible to transfer them and how?