Finding a way to duplicate existing items in a library when adding custom items would be very helpful.

Hi J Adrian, Thx. It would be helpful. Did you see my suggestion to also have the option to overwrite or replace existing Libraries (or existing Categories-- forgot to include that)? Several Finale 'expert' colleagues out there liked the idea, too. :) 

I strongly support the basic idea. Ideally, Finale needs to have a dialog in which each library could either be loaded or removed from the current document.

Such a window would also need to display where the loaded library's items are placed, e.g. "myharpexpressions.lib" -> "Expressions 90-100" or "myjazzchords.lib" -> "Chord suffixes 34-42".  With such a dialog, the control over library files would be greatly enhanced.

And, BTW, those .lib files need to be XML files, please. For easy comparison between contents and versions.

If the score already uses items from the library you are replacing, then the program would need to replace each expression in exactly the same code-slot as its corresponding former expression. Otherwise pee-existing expressions in the score could change. As much as I wish to see this option, I do not discount its complexity or expect to see it soon.

This would be very helpful. I'm sure it might be complex to code up, but I think it would definitely be worth the effort.