materials - copy/update to library - where?

I have my material libraries defined as  =(_USTN_ORGANIZATION)materials/ and <(_USTN_WORKSETSTANDARDS)materials/ 

when I open the library in a file, then make some changes to a material, I want to then push these changes back to the library for use across the project. 

As (_USTN_WORKSETSTANDARDS)materials is prepended to the list(and that organization is a read only location, I would assume that any library changes should push to here, however whilst a library somewhere accepts the changes, the libraries in the project materials dgnlib do not update. 

How should this work, where should my libraries be located?