Import file from another CMS (SharePoint) repository

Given:

Documents reside in various SharePoint Site Collections.

Book is saved to Site Collection #1

Using FrameMaker's CMS functionality, I am able to easily browse multiple repositories (each repository representing a connection to a different SharePoint Site Collection).

How can I import, via reference or copy, a file from Site Collection #2?  The options to browse to another repository, by URL, or by local file system are grayed out.  It would appear that I am only able to import files from within the same site collection that my book exists in.