I have ipod/itunes on two computers and two user names. The desktop has my old songs, I have since gotten a laptop and have built my music collection on it. I want to share my most current music on my laptop with my old computer, which is outdated.

Question

How do I clean up two user names and share most current music on laptop with the older computer and out of date ipod music. I have to do this carefully, so I don't lose the most current music library on the laptop?

Answer 1

If those older shuffles work and have the songs on them...
For songs purchased from the iTunes Store, you can use iTunes to transfer from iPod to computer.  The command (in the current version of iTunes) is at
iTunes Menu Bar -> File -> Devices -> Transfer Purchases from [name of iPod]
However, you may need to have your current computer authorized with the Apple ID (iTunes Store account) used to make the purchase.  If you do not, the purchases from that Apple ID may not transfer.
There are third-party methods and utiltiies (not using iTunes) to transfer song files from iPod to computer.  These should not care about Apple ID or that a particular song was purchased from iTunes Store or not.  If you do a Google search on something like "ipod transfer," you should get some links.
Once the song files from the two older shuffles are transferred to your computer, you can add those songs to your iTunes library.  Then, sync your 4th gen shuffle from the "consolidated" iTunes library.