When I try to add an instrument track in Cubase a drop down list of sample libraries appears and I can choose one to complete the instrument track creation.
BUT: What determines what libraries are in this list and how do I add to it. It does not appear to be a regular file structure from drives which makes me wonder where is the list coming from and how to edit it.
Here is a screen shot of what comes up when I am adding an instrument track. Its a list of players I can pick (Kontakt, Synchron, Play etc.). for the instrument track. But I was wondering how to add to this list as it is uneditable as it appears when creating an instrument track. Turns out I now understand this list comes from the Media Bay. But I still don’t know how to edit in the Media Bay to create and change this list that pops up when I try to add an instrument track
As already suggested, go in the VST Plug-In Manager and, for each instrument, you have a Hide option in the Plug-In information panel of each item listed.
Using it makes the involved instrument disappear from the available ones list when creating an Instrument track. AFAIK, you cannot add by yourself libraries or samples : only the samplers/players will appear if installed as VSTi plug-ins.
No, what actually appears is a list of plug-ins, which are installed and available on your system. These are not necessarily sample libraries (unless the sample library is wrapped in its own VST plug-in).
You seem to have a slight misconception of what really is going on. Maybe a look at the manual for the section of VST plugins and the plugin manager could prove useful.