Compare Music libraries and import songs from one library into another
I have a Music library on an external disk drive which is different from (and somewhat larger than) my System Music library that is synched to the Cloud. How can I compare the contents of these two libraries and import into the larger, external, unsynched library those songs in the System library that are missing from the external one? I've read the Music Help instructions about using Family Sharing to import from one computer to another, but I haven't been able to make that work.
MacOS 13.2.1 on a 2019 MacBook Pro
MacBook Pro 15″, macOS 13.2