As a general rule, first backup your data. You can either create an X7U (user file) or X7A ("all" backup file - will save libraries, user, and more). To create a full backup, follow directions here: https://yamahasynth.com/montage-category/mastering-montage-best-practices-for-backline

Under the heading "SAVING/LOADING BACKUP FILES".

To save just the user performances (and not a full backup), instead of choosing "Backup File" in the steps provided, choose "User File".

And now to the steps ...

Following: https://www.yamahasynth.com/yamaha-synth-rss/user-and-library

1) Press [UTILITY] > "Contents" > "Data Utility" > you will see folders of your current situation, select the "Performance" folder.
2) Press the "Job" button in the upper-right. This allows for you to select multiple Performances to choose for deletion. Delete the unwanted Performances (ones you do not want to place in a library file). From the docs:

You can delete unwanted Performances by using the "Job" function in the Performance folder (this does not remove Waveforms/Samples)

3) Once your user area has only the Performances you want to load into a library, save an X7L file. From the docs:

You have two options to back up your work, you can SAVE your data to a connected USB stick (for long term storage), as either a USER (.X7U) or a LIBRARY (.X7L) file.
[UTILITY] > "Contents" > "Save/Store" > set the CONTENTS TYPE = USER file or LIBRARY file.

You would choose the type "Library file".
4) Note: you asked for directions to "import" a Library file. I take it you just used the wrong term. When you create a new Library inside Montage, this is called "installing" a Library file. The act of "importing" a Library files means to move some (or all) Performances FROM the Library area TO the user area without overwriting anything in the user area.

In order to install the X7L file you saved in step 3 - from the docs:

At this point, only a Montage can create the .X7L file. So to create a LIBRARY you must assemble what you wish to place in that Library into your USER area. From the USER area you can SAVE as a "Library File" - this creates a .X7L file on your USB stick.

Once you have that file (editoral comment - after performing step 3) ... You can then install it to one of 8 Library locations. Please note: first you create the .X7L file, then you must Load that file to accomplish the installation of the data. Read again if that's confusing. Once your assembled data is in a FILE that has the .X7L extension, then and only then can you write that data into the Read Only Memory area that is a Montage Library. (A .X7U file cannot be loaded directly into a Library).

Libraries can vary in size. The Bosendorfer Library comes as a .X7L file. You can install this in your Read Only Memory by loading Content Type = "Library File". This does not overwrite anything in your USER area... It goes straight to the special, lowest numbered empty Library location."

The docs have a picture showing you where to go:

To get here, press: [UTILITY] button, then "Contents" -> "Load"

The Library you saved in step 3 will be shown and pressing on it will load (install) the library into the next free library slot.

Thanks Jason.
Library "file" instead of "Folder" is where I missed it. A group of performances that is...
thank you for your reply.
When I have time, I will create a 'How To", all the steps I have successfully accomplished in getting Sample Robot created and Waveform Editor adjusted performances to work, step by step.
There seems to be zero support for either and Sample Robot still will not allow intact performances to be moved from Library to User
without W.E. Such nonsense to accomplish. My Triton did it all in 3 simple steps.
cheers