The idea behind libraries is that they are, in fact, libraries. They're stored in non volatile memory as a single bank each (8 can be stored on MODX). You can, however, copy single performances to user memory. The user banks have the same "issue": they map to user memory as a whole structure. It would require an immense memory juggling to implement merging user bank libraries while keeping existing data.

For ultimate flexibility, you should be in the habit of "always" saving your content as a user file AND a library file. And also, while you're at it - save a backup file that will store your entire MODX in a single file (libraries, user, arps, etc).

Because in this case where you would want to load just one Performance out of backup of your user area from the past - AND keep your current user bank in-tact. What you would do is load the backup as a library in an open library slot then import any one (or more) Performances from that library into your user area. This would not clobber anything in your existing user area and you can pick-and-choose what you want from the file after it is loaded into the library area. Then you would/could remove the library you just loaded as a means for getting the one or couple Performances into your user area.

That's the way.

On the subject of being able to edit a library one-by-one: I understand you want to do this. And I understand why you'd want to do this. It just can't be done. Picking up on the analogy.

The idea behind libraries is that they are, in fact, libraries.

... think of an author of a book. When he/she is writing the rough draft and revising the book - before it's been published - this will all happen at his or her desk or on the backs of napkins here and there. The author's desk and napkins and such are, on your MODX, the user bank. Just like the author at his/her desk can freely edit any part of their draft copies of the book - you too can freely edit any Performance while at the equivalent area of using the User bank.

Then the author turns in the final copy of their work after all editing and review has been done. The publisher takes over and books are made. These books find their way into stores and libraries. The author cannot make any changes to these books. Each line of each book will always and forever have the same content. This is the same as MODX's library bank. You can't change these Performances.

If the author does want to change something in the book - they can grab a copy of the book from the public library and take it home (back to their desk) and then pencil in changes. This would be the same as you importing a Performance from the Library (or [STORE]ing a copy from the Library) to the user bank. [STORE]ing is slightly nuanced in that it does not copy custom waveform data from the library to user area. Not all Performances have custom waveform data so sometimes [STORE] can be the same as an import.

The analogy of [STORE] vs import here would be MODX [STORE] would be like the author taking a photo copy of the book and bringing that home to their desk to edit -- while MODX importing from the Library to user area would be like the author actually checking out the book and bringing the physical original book with them home. Say the author's book has no special features - then the [STORE] vs import (photo copy vs. checking out the book) would be the same. Say the book was a "pop-up" book that had pages that would create "3D" shapes when you opened certain pages. The photo copy would not be the same as the original book in this case since the photo copy wouldn't "pop up" like the original book. For some pages of the book (some Performances) it may not matter since they don't have pop-up type features (Performances with no custom waveform) so [STORE] would be the same. For some pages, it may matter. I could go further and cover the nuance of "pointing to" vs. "embedded" for the waveforms - but won't.

... so Yamaha chose to present to you a system that's as described above. That's just the way it is. What you want to accomplish can be done - but takes a few extra steps to do vs. what you envisioned originally.

The USER BANK is your "work area" -- loading data to the USER Bank will overwrite data in the USER Bank.
The LIBRARY is ROM (Read Only Memory)... as the name implied - you can read only.

You can assemble sounds in the USER BANK and ultimately create your own custom Library.

You loaded sounds to a LIBRARY location - first. Fine. You could possibly have loaded the data to the USER bank (let's state there is another way to approach this but let's follow your method first).
You can play through the Library and decide, as you did, that some of them are keepers and other you wish to discard.

Immediately you run into the first two important statements. You cannot just simply delete READ ONLY data. You can only Read it.
And since when you load new data into the USER Bank it overwrites previous data in the User Bank... what can you do when you want to assemble data from multiple File sources?

You can assemble sounds in the User Bank - once you have data loaded to the USER BANK you can add new sounds to it by using the "LIBRARY IMPORT" function.
Data Loaded to a Library location never overwrites anything. Data Loaded to a User location always overwrite data.
Library data Imported to the User Bank is the SOLUTION - it allows you to pick the data you wish to keep and *adds* it to the lowest numbered empty locations in your current USER Bank area.

The "Library Import" moves data from the Read Only Memory (Library) to the User Bank. It does so (importantly) without overwriting data currently in the User Bank (so it is the method to add data to your current User Bank data). It also will make sure that any custom Waveforms and custom Arpeggios come along with your selections.

The important difference between simply STORING a Library Performance and IMPORTING that Library Performance is the duplication of these custom components. They need to be redirected to the USER BANK and the association between the Waveforms and the Elements within the PART and the Arpeggios and the Part must be maintained. The Library Import feature redirects the Waveforms and the Arps to USER locations... and maintains the relationship between the custom data and the newly imported Performances.

Once you have assembled all data to the USER Bank you can SAVE AS... in this case, saving as a LIBRARY FILE. The File you create from your USER Bank will include instructions to burn the Waveforms and the Arpeggios into your Read Only Memory so that they remain associated properly. It is just a file. But it will contain all the items that you assembled. You can DELETE the Library you previously installed, you can Initialize the User Bank. Finally, LOAD your new Library File - it will contain everything you assembled.

USER Bank can include:
640 Performances
256 Arpeggios
2048 Waveforms
256 Motion Sequences
32 Curves
8 User Banks of Live Sets (2048 slots)
8 MicroTunings

LIBRARY Bank can include:
640 Performances
256 Arpeggios
2048 Waveforms
256 Motion Sequences
32 Curves
8 User Banks of Live Sets (2048 slots)
8 MicroTunings

The difference between a User Bank and a Library Bank, is the LIBRARY Bank remains always. Is never ever overwritten
A User Bank gets overwritten each time you load a new User Bank File.

Hope that helps.

thanks to all of you guys, now the concept of Library is very clear! HAPPY HOLIDAYS to all !!