If you read DRAFT Administrator Application User Guide.pdf - Chapter 2.4 Searching Libraries - it says:
When a DRAFT application user attempts to create a new element, for example, a symbolic
label, the application searches for relevant Libraries in a specific sequence. It looks at each
LIBY in the DEPT in the listed order until it finds one that contains appropriate type of
Library. It then adds this LIBY and all subsequent LIBYs to the scrollable list on the Library
form until it finds a LIBY which does not contain a relevant LALB. No further searching is
carried out.